After weeks of waiting and monkeying around, finally got the sucker in there. Really only took a few hours to do including removal, cleaning, de-rusting, and installation.
The good: fold-down seat on a car that it was not offered in. Helps with long items that simply won't fit in the trunk. Little Bazooka bass tube can now sound off freely into the passenger compartment without being dampened by foam and plastic.
The bad: Fold-down seats have big metal pans that hold the latches and give the seat back strength for when you put heavy items on them. Sadly this adds quite a bit of weight including the hinges. I estimate at least 25 pounds (probably more). The seats I got from the salvage yard was a bit rusted so I used rust converter to clean it up.
The ugly: You won't find 4-door seats with matching SE-R interior cloth. I used an upholstry paint to give it a dark grey hue. It didn't turn out the way I would have wanted it. Material dye would probably be much better to retain the nice feel of fabric. The wheel wells will show when the seats are in the upright position. In 4-door cars, they would be covered with plastic trim. I have these but it will need some cutting to get them to fit with the inside panels.
Conclusion: User friendly but performance hindering. If I get tired of it and feel it is too much of a burden, it'll be going into my other SE-R. Cross brace will remain but with loosened screws for easy removal. Random Thoughts rSTB will remain until Josh's rSTB unit arrives.