A thread on the Mach-II Google Group about moving from Procedural style coding to Mach-II has been a great read. A recent post from Matt Woodward regarding ColdSpring (and too many visits to Ben Nadel's blog) inspired a new ad for ColdSpring.
Honestly if you don't use ColdSpring you're doing things the hard way. Don't think of CS as a framework in the same sense as Mach-II--if all you're going to use it for is dependency injection then the learning curve is very small and it will save you TONS of headaches. Pushing back by saying "one framework is enough" is kind of missing the point of CS since it's not something you really have to spend tons of time learning. I taught the basics of it to my team at work in about 2 hours and they all seemed to get it.