Ok. Probably seems like we’re busting your balls. But we’re not. Just want to make sure you get the best return on investment. As HD said, matching sub to speaker brand isn’t necessary whatsoever. Most “speaker” builder tend to make subs as an afterthought to accompany their speakers anyway, so they usually perform as such. Also, the wattage thing shouldn’t be a concern either. Speaker sensitivity and overall design will determine performance, so don’t get stuck on those number too much.
IMO, choosing the speedwoofer over the klipsch(and probably infinity too) will be similar to going from no sub to one. There’s MUCH more to bass than boom, and the RSL is going to be more linear, and more tightly controlled than either of the other two. It’s probably the perfect sub/s for your room. No, I’m not interested in watching you spend money either, lol. But I’ve experienced budget subs, and can tell you from experience, just skip the low hanging fruit. The juice of better subs is worth the squeeze.
If you do get the center(which I think you should) you can still run 3.1 without surrounds. However, it probably wouldn’t be long until you addressed that too!!!! Lol.