I have both. A 86 vintage ULA in 257 AI and a Montana in 7-08 of uncertain vintage.
I bought the Montana because its stainless steel, light weight, good stock, light weight. I ended up buying used after waiting for Kimber to make 7-08s for about 10 months. This was in 2008. To say that they were unresponsive to my questions about production is an understatement, despite my $1k deposit. However, the rifle I ended up with is as advertised: light, accurate, good stock fit(for me). My only real complaint other than poor customer service is that the stainless does stain quite easily. After one day of wet rainy weather rust started to frost on the surface. My stainless ruger 77/22 can take the rain with no problem. Perhaps this is just my Montana or they use a stainless with less corrosion resistant properties.
I ended up buying the ULA model 20 from an auction primarily because I felt I could do better than the Montana. I got a great deal on it and encourage you to shop around. There are some great deals both here and at the other internet gun sites. The gun was practically brand new and shoots very accurately as long as I do my part. I am still working up loads for it. The differences were discussed better by JB and BobinNH than I can, but I will say that I would definitely buy another ULA or even a NULA, rather than another kimber.
