When I used to advise people on upgrading computers, I always tried to force them to think ahead. If you have a p90 in a humbucker route and you want to go back to humbuckers at some point, you're good to go. I think this is key.
If you try to do it the other way, I'm not sure that gives you as many options.
When I ordered my last PRS, I couldnt' decide on soapbars or hummers. But, I don't just preach that logic, I live it. So, I got the McCarty with the hummers and put Phat Cats in it. One day I might put some other hummer in there, (not likely) and I'll have some really great choices.
There just are not that many great mini-humbuckers out there.
Sorry for repeating myself.