The Rythmik G25HP, JTR RS1/2400 are fairly small subs
(They're really not but obviously this does come down to what you're comparing them to!)
So the question is, rather than look at the room dimensions, as any of those 10% subs can easily deliver, is if I put a little bit more money in then just get an end game duo which will also be future proof if and when I move house and potentially get a dedicated HT room.
You're probably set on this logic but FWIW my inclination would be to focus on what you want now rather than guessing what you may want in the future. If you end up with a larger room you may decide you'd be better off with more than two subs anyway, particularly if this was with providing a good bass response over more (or more widely spaced) seats in mind. I'm not in any way trying to tell you how to spend your own money here but just giving you something to consider.