Tom;
I have a modified 2002 SE-R auto, which is essentially the 5 speed SE-R with an automatic transmission. The 5 speed SE-R is actually faster than the 6 speed Spec V, primarily because it is much lighter. They have 10 less horsepower (dyno sheets show this difference to be less), but that '10 less horsepower' has seemed to help the 5 speeds be more reliable than the 6 speed Spec V. A few guys who can drive have ran 14.9s stock in the SE-R 5 speeds (actually they removed part of the airbox and restrictions and a few other parts but no out of pocket expensive was spared so I still consider the car essentially stock). As you can imagine, Spec V guys were not happy.
I have driven an SE-R Auto (actually I have driven 3 in total), and multiple Spec Vs, as well as a NISMO tuned Spec V. I will try my best to give a good summary.
Now, the main differences are this:
-16 inch wheels, vs 17 inch wheels: The tyres for both the SE-R and SE-R V are crap, and should be a priority to be changed. Both wheels are butter wheels, and 17 inch wheels of the Spec V can bend very easily. The OE tyres are Firestone Firehawk GTA-02s for the SE-R, and they are horrible (Continental Sport Contacts2 for the Spec V which aren't much better). I decided to use the Firestones as winter wheels, and used a 7 inch wide wheel with Yokohama max performance summer tyres for all other times. When I put the Firestones back on for the winter, I lost control when hitting standing water which caused me to have an accident. I simply became accustomed to the excellent performance of the Yokohamas, and was not used to the crap Firehawks as the Yokohamas would have had no trouble with the amount of water I was faced with. It was a costly decision so I would reccomend having both summer and winter tyres to maximize enjoyment and safety. Also, the Firestone Firehawks suck in snow, although they are considered to be a radial.
-Suspension: The Spec V has a bit stiffer suspension; I can tell a difference but it is miniscule. The SE-R in either form is 'bettered' when the suspension is upgraded (Tein rules).
-Interior: This is part of the weight increase. Side airbags, a stock subwoofer (which sucks, and the sound package can screw anyone over who looks to upgrade their audio system in the future), a sunroof (this adds a lot of weight and decreases structural rigidy greatly, so avoid this if you want to mod), and different seats and dash panels add up for more weight. Personally, I like the look of the SE-R interior more as it is more plain and attracts less attention in terms of theft. It is also much easier to clean. While the sunroof, sound and side airbags packages were available on both the SE-R and SE-R V, the Vs were much more likely to have them. My car has none of these options, and quite frankly I am glad.
-Transmission: This is the kicker for weight and problems. Significantly more weight, and the SE-R essentially has no need for a 6 speed. The older 6 speeds were very problematic as I am sure you have heard. Some of these were annoying sounds, all the way to defects which warranted a transmision replacement. I know quite a few 5 speed owners and I have not heard of a single problem.
-"10 Horsepower" difference: This '10 horspower' seems to have a lot more effect than just power. The SE-R is faster because of weight, but the tuning of the Spec V is what gives it more power. It also seems to have more problems. The SE-R base seems to have fewer problems with the precatalyst. I did not have problems until I was fully bolted minus the stock exhaust manifold. SE-R bases seem to have fewer problems than Spec Vs.
-Rear Seats: The Spec V's seats will not fold down all the way if they have the sound and sunroof package. The SE-R will.
-Steering wheel: The Spev V has 2 grips which the SE-R does not. Both are still leather wrapped
What you absolutely must know
All QR25DE engines (the 2.5 liter engine that is available in the Sentra LE (discontinued); the SE-R base; the SE-R Spec V; Altima; and X Trail are prone to a problem with the secondary intake runners. These open up at 5100 (IIRC) RPM, and many people confuse this with VTEC, which it is not. There are 8 screws, 2 on each butterfly valve. Nissan never secured these well and they are prone to come loose and eventually getting sucked into the engine. Nissan has not and probably will not issue a recall. The solution is simple; remove the top portion of the intake manifold, remove these screws, and Loctite them. If screws are missing, then a real problem exists. 6 of my 8 were loose. Be sure none are missing before purchasing any QR powered vehicle.
Also, ensure all recalls were completed and that the car is not burning oil. If it is burning oil, it is an indicator of a defective pre-cat which has destroyed the rings. This can be fixed in 2 ways: replacing the engine, or removing the entire head and replacing the rings. Both are expensive and Nissan generally covers engine replacement under warranty, but if this happens, it will cost you at the least a lot of time and a head ache. The best solution is to be sure the precat is in fine condition and to replace the stock exhaust manifold with an aftermarket header. Other recalls include the ECM foam recall and the floormat recall.
The car has CVTC (Continuously Variable Timing Control) which is different than VTEC (Variable Valve and Lift Control) because it is as stated, continuously variable hence it cannot be adjusted or tampered with. Prettymuch it is there, and there isnt much that you can do with it. It is not directly related to the sound at 5100 RPMs, as that is the butterfly valves opening up.
While 2002 was a bad year for many Spec Vs, it did not seem to be a bad year for the SE-R, or other QR powered vehicles. If you are looking to modify, the SE-R base is superior to the Spec V in every aspect except maybe in cosmetics. If you go for an SE-R base, I would be willing to bet it has been driven hard much less as well. I think you have made a good choice, especially if you want to mod.
Hope this helps and goodluck on your purchase,
-Zac-
Information on the 2002 SE-R 5 Speed MT w/ QR25DE
I dont think anybody could have said it better! 
. I will also secure a list of TSB's to hassle the owner with 
good fun.
Linear Mode
