The Epic and some geometry thoughts/questions

The Epic
Really dug the 2010 Epic that Tyler let me ride on my 2nd lap at Bonebender, but it was really disconcerting on the first 2 miles because I would mistake the threshold "break through" of the Brain suspension for the rim making contact with roots and rocks (which give you a very sick feeling in your stomach early in a lap).
But once I got used to that it was all gravy.
Shifting was smooth and crisp. Tylers Epic is spec'ed with XT/X9 and I feel safe to say that it was under 25 lbs.
I will say that I was not as comfortable on the really technical sections as I was on my SS. Maybe its the steeper angles, higher BB, longer travel, etc. I just felt a bit of trepidation, right as I was getting to hit that little rocky off camber stairstep right by the lake (you know what I am talking about). I rolled through it on the SS with nary a thought and caution blowing in my wake.
I will say that it was the cats PJ's to be able to stay seated and roll through all the chatter that would of had me standing on the SS.
Overall I would give it very high ratings. I was really impressed with the new SID from Rockshox. I have always thought of SID's as a bit noodley, but if I had not seen the pictures I would have sworn it was a Reba. Both now have 32 mm stanchions.
Not as "harsh" as the Top Fuel, but a little heavier.
Geometry
So I am constantly caught in that proverbial "no mans land" in frame sizing between a Medium and a Large.
I have rather long legs for someone of my stature, and can typically jump onto the bikes of people that are 2-3 inches taller than me and not have adjust the seatpost height (this also may have to do with the fact that I tend to "reach" with my feet in my pedal stroke). But, I am strung out like a Seattle hooker trying to cover the top tube on these bikes. Standover has never been a issue for me.
In cross bikes I tend to defer to larger frame sizes since running up a ton of seatpost leaves me all hunched over and the drops out of reach given my flexibility (or lack thereof), and I can compensate by using a shorter stem to even things out.
However, I am not sure that I will be comfortable doing this on a mountain bike. This is compounded by the way manufacturers size their frames. A largeTrek Top Fuel has a longer TT (625mm TT) than a Large Specialized Epic (615mm TT) , but the Trek comes in 5 frame sizes as opposed to the 4 frame sizes of the Epic.
Big P's has been doing a valiant job of trying to keep us Riding for the Brand. I have been told that I can have this bike now that its done making the rounds at shows.

But its a large and has a 641mm TT. That would have me using a very short stem.
Why not just order a Medium? Well expected delivery for any DSR's that are not already in country is going to be late summer.

So thoughts, concerns, insightful input? What should I do? Sooner or later I will run out of friends and acquaintances that will let me test ride their bikes.