I’ve been in Turnover and Aldon shops. The price is fairly comparable. I’m curious with only four developers what is your PCI level? If you are a level 3 or 4 you might be able to talk your PCI auditor into letting you get away with a homegrown change control system as long as it is administered and all PCI related code reviewed by someone that doesn’t code for production. If you can also can show that the production code cannot be accessed for update without management approval, that you maintain and track a copy of every version and that programmers don’t have any more than read access to production they might let this fly.
I’ve worked with the 3 you’ve mentioned and would rank MKS, Turnover, and Aldon in that order in terms of functionality and ease of use. From what i recall, the price is also in that order as well as the level of support. I’m at an Aldon shop now and the support is still sub standard compared to the other two but for a shop your size it may be ok.