the big one: how do you choose speakers? By what features, data?

Unless one is considering extraordinarily difficult to drive speakers and a requirement to play at extremely loud levels, I would expect 100 watts to be plenty, and, power is not a concern.  However, amps are critical to the sound of ANY speaker and quality of whatever watts it delivers matters a lot. 

I personally like low-powered tube amps the most, assuming they are used with compatible speakers, because they tend to be lively, engaging (keeps my attention), and at the same time do not sound edgy or hard and brittle.  Most high end, high-powered solid state amps are not offensive ((not "grainy" or "harsh" as some tube lovers claim, but, to me, they sound a bit lifeless and unengaging at lower volume levels.  I tend to not like most very high-powered tube amps because they have a hardness or "glare" I find a bit annoying in long-term listening sessions.

that is not to say I don't want (to try) another amp but it's definitely not my bottleneck. My current speakers are very musical, but a bit muddy and have too much bass at the expense of the midrange. Which is probably by design, for this price range and components, it's giving the listener a lot of bang - literally

IMO many audio buyers allocate an excessive amount of money towards loudspeakers neglecting electronics/source/cables and room treatment. The outdated theory of spending 50%(total system cost) on speakers was created by the industry to keep one upgrading(unhappy) electronics and source components. 

Nobody asked, but a famous reviewer Jay's Iyagi (from Canada) finally took notice of the OGY. I say this because Closer Acoustics is an obscure boutique brand in Poland. He must have read my comments or something. There's no way he would have heard of the OGY otherwise. Yeah, Jay is not the most trustworthy reviewer out there, but I enjoy the validation nonetheless:

Review here

I agree with this review wholeheartedly. To paraphrase: The bass is light but very fast and clear. You should use a sub. Midrange and Treble are flawless, impressive regardless of price. Imaging/soundstage are a great deal better than most 2-way bookshelf speakers.  

I'm just worried that I'll have to bite the bullet and finally buy a decent tube amplifier to get the most out of these speakers. 

I'll confess that it's a bit courageous to order these speakers blind and deal with FedEx international shipping. 

I´m a motorcycle enthusiast that used to race / ride Enduro. When you buy a motorcycle for that use, you get pretty much 90% of what you need.  Set the thing according to your riding skill level / preferences and off you go !.

  Going back to audio.  Not the same game, when you get bit by the music bug and get into this, you just paid the admission ticket for a journey!!! As several persons have mentioned, this  is a long, patience frustrating, economic stressing,disappointment causing experience that gives you some golden nuggets in the process to keep you hooked.

You hear magic at a friend´s or dealer place and you get those speakers home and  the oops start !

This is a personnal perception activity so it will  depend on the reproduction chain you use to listen. Room, speakers, power, source cables, you name it  they matter.

Good luck with your own musical journey... Keep a sane a approach and do  not take it too seriously, enjoy. You are not alone. Cheers.