I always seem to be following dodgealum and agreeing with him. I use an ARC Ref 75 Power amp and was looking for a matching Pre a few months ago, I tried the LS 27 and Ref 3 from Arc and the former was slightly better. Then I tried Modwright and I agree with Dodgealum the LS100 is warmer and the LS36.5 more detailed and neutral.
I compared the 36.5 with the REF 3 at different dealers over two days, which is about the limit of my aural memory and I thought the 36.5 was better than the REF 3, not night and day different, but better. The Modwright was a good bit cheaper, more compact and better looking too. I heard the two box version of the 36.5 as well and that really was good, but I could'nt run to the cost.
I was told by the UK dealer that the one box 36.5 can not be converted to the two box, but someone on the Gon corrected me and said it is possible, so that gives a useful upgrade path too.