I just posted this on another thread where a guy is looking to replace his Fat 50s in his guitar. I thought it was important to add here:
"It took me a long time to learn this, but you are better off starting off with a crystal clear, bloomy, chimey sounding strat and adding a little bit of grit with a pedal or your amp. That is easy to do, and a solid "clean" foundation is important. Getting that silky thick pure clean strat tone becomes unnecessarily hard the "hotter" you go down the pickup line. You have a great set of pickups in the guitar now (Fat 50s), I don't think I would justify the cost of switching them out before at least experimenting with the guitar for a bit. Just my HMO after 30 some odd years of soldering pickups and putting together guitars."
Sean