quz if I buy an expensive 7 string now and I find out that I don't even like 7 strings its kind of a waste of moneyActive pickups certainly don't limit what genres you can play at all. My EMG808s are perfectly versatile. I jumped from a six to an eight with no idea of what I'd play besides jamming along to Meshuggah.
After nearly two years, I found the answer to what I'd play with the two lower strings: everything. There's nothing I haven't enjoyed playing on an extended-range guitar. Just ask yourself, is there anything you want to play with the extended range? You said you already want to play some progressive metal and stuff like that. I'd say take the plunge. (But I don't see why you shouldn't get a good quality one?)