One of the things we need to understand is
what do we want from a release train?
1. Is it simply a release of the latest and greatest stuff Eclipse has?
2. Is it a set of plugins / components that are known to 'work together'?
3. Is it a co-ordinated marketing exercise?
4. Is it a snap-shot in time of what we have?
5. Is it something else?
There is nothing wrong with components doing their own release and coming together 1+2 times a year (release plus SRs). In this case the latest and greatest are in the SR0, SR1 & SR2. We could also approach this from a two-stream perspective. Latest and greatest is in the Milestones, and the SR0, SR1 and SR2s are the LTS versions. Both of these will work, but I don't think we should mix & match approaches.
I'm sure with 71 projects in the release train, we'll arrive at 71 different meanings for the train.
Doug, in the case of CDT, could you consider M4 & M7 your 'releases' (after a few rounds of RCs of course)? What version of the platform do you want for your mid-term release (i.e. will Dec 2013 build on Kepler or Luna)? Do you expect / need marketing support for both releases? Do you expect both releases to be of the same quality (will vendors build on both)?
Just a few more questions to hopefully help drive the discussion :-)
Cheers,
Ian