I think that's a tad optimistic considering 2.0.0 is still in it's alpha stage ;)

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and when it comes to stable? or suitable to use?

a few plugins for v1 works in v2.....

There will be plugins that will be compatible with v2 as time goes on.

v1 plugins' compatibility highly depends on its authors. Right now, I'm sure many of these plugin developers decided not to upgrade at least until v2 reaches RC release (RC = Release Candidate), or something similar (whatever 'tag' b2evo team uses).

Since its alpha, many stuff can still change. The more branches you have, the more people you have support. Which will be hard especially that not everyone upgrades to a newer version religiously. And many if not all, do not use revision control systems like SVN, CVS, or monotone. So its even harder for these devs to track their branches and tags/releases ;)