Most of my collection are G1 or Classics so I do have some repaints, like the e-hobby exclusives - those stay MISB.

I don't plan on getting any of the Japanese Classics except for Megatron, and only because he's G1 colored (quite frankly, I think his design sucks). I could care less about minor paint changes.

And I do find myself buying some reissues of characters I already have. Not necessarily because of new paint schemes but because they display well MISB. For example, the different Pepsi Primes, the Encore reissues, etc.

 

I prefer to get one version of each mold unless it's a mold I like and they represent a bunch of characters that are supposed to be similar (i.e. Seekers). I think the only one I've bent that rule for so far is Movie Jazz as I currently have three versions of him. Though one was bought for his weapon and will be used with the intention of being Kitbash practice so I can "g1-ify" the G1 repaint. I also get around having two of the same molds by giving them a slightly different transformation (my g1 jazz keeps his shield on his back with gun over shoulder and movie one has shield on shoulder with FB jazz's gun) and by making them two different characters (G1 Jazz is G1y while Movie 'Meister' is his movie self). Though if the premium version looks that much better then the original movie one, he'll just be number 4 in my collection leaving me two Jazz's to destroy in my fruitless attempts to customize something.

But other then that, I have a one mold per bot rule unless it's something that can be changed into a different bot.