1. I would say the latest version of CbB is generally the most "stable" ... but I register there are many different opinions as to what is the most stable version. I have the impression that the CbB releases so fare have been mostly bug-fix related.
2. I'm using both CbB and Platinum. Reason for this is two fold. First by also having the latter installed, you gain features otherwise lost in CbB. Secondly, there is no 32-bit version of CbB ... and I have projects that are heavily dependent on older 32-bit plugs ... and theses seem to work better in the 32-bit Platinum version.
I use the CbB version as that is the coming thing, and I'm curious to see it's development. Particularly how the connection with BandLab and on-line publishing and collaboration will turn out.