IME, Blake is definitely a bona fide minimalist and quickly converted me into one as well. however, there are still some out there that are convinced that there is no overlap in their bags, and if it works, then theres no big deal.
overall, if you like your set up and if three separate discs are easier for you to understand than variations on one mold, then by all means, go for it. but minimalism has reduced my second guessing since i cut down my bag to 4-5 molds (with 20-22 total discs). if the shot is between 200 and 220, i know im grabbing a wizard...it just depends on the one that is right for the shot. this also cuts down on readjusting my grip for a different disc. if its a midrange shot, it will always feel like a roc. drivers will always feel like orcs....because they are all orcs.
its just one of the many philosophies behind bag building. i adopted it and havent looked back....
now as for your new question that i so blatantly disregarded,
Rams are discontinued so if you lose them, they will be difficult to replace...instead of them, i would go for the EXP-1, X-CLone, or the Firebird. so far, i have found predators and firebirds to be the best overstable discs currently on the market. so choose one of those three, and keep the rams if you like the way they look (and also in like 10 years someone might be jonesing for them so you can make a little money on ebay)
Teerexes are a lot of disc for someone with your power (especially if it is a Teerex-X). I throw a bout the same d as you, and the teerex didnt add anything to my game. i know a lot of people like them, i just didnt.
The valk seems like it would make a good control/understable driver in your bag. since hte crush, surge, and destroyer are all really long drivers, they are more difficult to control than the valk. and once the valk beats in a little, it will go from a straight to a straight/turnover/hyzerflip disc and be very useful on a course
i am by no means an expert, just tossing in my opinions and thoughts...good luck