Mike,
I have had all three 250's in my Naim set-up. I have an orig. 52 and have had a chrome, olive and 250.2 in my system. The chrome vs the olive is by far the biggest jump. The olive has bass slam, and rhythm in spades. I recently moved to a 250.2. If you want to stay with a 250 then the easiest way to decide is deter. by your music taste. I found the olive 250 is better with rock, elec. blues while the 250.2 is better with acoustic jazz, class. esemble. Both are good for symphonic music. The 250.2 is good at subtlety and nuance. I can't comment on 135's but I have always heard they sound great.
If you are interested in an olive 250 let me know. I still have mine and will be selling it soon.
