I have both the Curado and Curado BSf and love them both, that being waid I played with the Quantum pt 600el and was extremely impressed to say the least. Noticeably Smoother than my BSF. I don't know how they'd stand up to a big nook though.
My buddy and I have this ongoing debate about which low-pro baitcaster he "needs" next. I have two Curados and one Calais for steelie fishing. A new Curado runs around $110 (not BSF) while this Quantum he's looking at, which supposedly is their best one, runs at $150. I have a Quantum that is a nice back-up reel, but I mostly use it to walleye fish. It's nice, but not even close to a Curado.
Would you spend the extra $40 for a Quantum or would you go with a Curado.