Realistically, will the Spendor S 3/5 work for me?

Sonically, though I have never heard them, I believe they are quite in line with what I am interested in. But it's their size and low efficiency that I am wondering about and how they would work with my amp and in my room. My room is 13x22x8, which is what, a medium to large sized room? My amp is a 50 watt LFD Mistral integrated amp, which is not a power house nor is it a wimp either. I listen to Jazz, Classical, Ambient, vocals. I don't listen to music all that loud really, usually kind of a moderate volume, not soft but not blaring loud either. My listening position is about 10 feet from the speakers (certainly not nearfield obviously). I would use them with a well integrated sub.

My question is, given my room and my amp, music and listening habits, does anyone have a general sense if they would work for me? I once used a small pair of Paradigm Atoms while waiting for a new pair of speakers, which are similar in size to the S 3/5, and was very pleased with them in regard to volume but then again they have an efficiency rating of 89dB compared to the Spendor's 84dB. I know I would have some limitations with volume and all that, but realistically speaking, would I likely be underpowering them, possibly suffering as well from the room size, which could make them sound strained or even closed in? I like a warmer, more natural and laid back sound but I'd hate for them to sound too closed in due to lack of power and my room. I know going for another amp would likely alleviate the problem here but I really like this amp and would like to not get rid of it. Any insight would be appreciated much.