The non fire feast version
I think my concern is to climb faster and not worry about coming down in speed.
which 303 clinchers?
Honestly, if your rides are up and downhill then none of the wheels you mentioned will be faster over the course of a complete ride. The last generation before the Firecrest 303s applied a fair bit of the FC technology and aren't all that heavy.
This has me a little concerned. I focus on three things here:
(1) you want carbon clinchers
(2) you are considering the non-Firecrest version
(3) you seem to indicate that you like to climb but that you take the descents slowly.
Why am I concerned? Because if you prefer to descend slowly, that means you are going to be grabbing the brakes a lot, if not riding them for prolonged periods while you descend. That's not a great idea in general, but normally not fatal (I see guys doing this all the time while descending the canyons here in SoCal). BUT if you are doing this on carbon clinchers, particularly "previous generation" carbon clinchers (with Zipp, that means pre-Firecrest), then you are running a serious risk of overheating your rims to the point where the resin weakens and all that force your clincher tire is exerting on the rim bead will deform the rim and cause it to fail. This is not something that is a "theoretical" or "1%" risk - basically, if you consistently overheat older carbon clinchers, you WILL fry the rims at some point... Whether that's ride #1 or ride #10 all depends on exactly how much you're braking on them, but it WILL happen.
While I wouldn't recommend carbon clinchers to anyone who does steep or prolonged descents and uses a lot of brake doing so, at least the new Firecrests use a resin specifically designed to handle high heat. Same with the Enve SES wheels. But until a couple years ago, the manufacturers didn't really have an answer to this problem (other than to lay off the brakes!), so previous-generation carbon clinchers might not be the answer for you.