Harbeth 30.1 or 40.1

Very good information, than you every one.  I always want to try McIntosh gear.  And I am planning to get the MA252 hybrid to go with the Harbeth.  The Ma252 is rated as follows:

Power Output per Channel
100 Watts into 8 Ohms
160 Watts into 4 Ohms

Maximum Output (Balanced / Unbalanced)
8V Unbalanced

i read Harbeth needs good current, but this is often not listed in the specification.  Is the MA252 good (enough) for 40.1?  Or I need the more powerful Ma352?  That goes into the total cost consideration.

I owned 30.1's and now own 40.2 anniversaries.
My answer is, it depends on how serious you are about music listening.  For me, sitting down and listening is the highlight of my day.  I listen actively and lose myself in the music.  If I were buying speakers for a common living area where I was unable to listen this way, I would probably choose the 30 series as they are smaller and still sound amazing.  
For me the 30.1's were fantastic sounding speakers, but left me wanting more bass.  My room is smaller than yours (12x14) so you definitely don't need to be afraid of the 40.2's.  They will sound great in your room with proper set-up.  
I ran a sub with my 30.1's and really liked the sound, but eventually I grew out of them and purchased some 40.1's.  The difference was not subtle.  I loved them so much and had no intention of upgrading until an opportunity to buy the 40.2A speakers at a great price came my way last year.  I am so happy I made this move.  I do not know if the new XD model is better than the anniversary version but I am not even curious about that.  The 40.2 line is the pinnacle of sound for me.  
I don't regret the journey I took to get here.  In fact, it was the right thing to move through the line-up, as it has helped me understand the difference between these models.  
That said, if you have the means to get the 40.2's I do not think you will be disappointed.  

@snackeyp dis you also upgrade the amp when upgrade to 40.1?  What amp did you use?

Long time 40.1 owner here.  Your room size is fine for 40.1's... and no, you don't need a powerful amp... especially for listening to jazz and vocals at moderate levels.  A good quality amp (I prefer tubes) with 75 WPC is all you need.  I've also owned Harbeth SHL5's... but they don't compete with 40.1's in my experience.  

@gte357s 
My amp was a Lyngdorf TDAI3400 when I got the speakers but after that I tried an LFD NCSE 3 and prefer it.  It’s a solid state amp that sounds more like tubes.  Great amp, but very simple, and lacks the convenience features of most amps, most notably a remote control.  My second favorite amp with these speakers is the Primaluna EVO 400.  I might buy one in the future as a second amp because it’s really that good.