I stopped by both shops today.

The guy at the Giant shop said he wouldn’t recommend buying the Talon with an idea of upgrading the fork down the road. He said it would require a wheel upgrade as well, due to the switch from quick release to though-axle. But he wasn’t trying to upsell me – he actually said he thought the Talon would give me many years for the type of riding I’m looking at.

The guy at the Kona shop wasn’t quite as down on a future upgrade; he said it wouldn’t really be much extra work to upgrade a wheel hub. But he also said that he thought the entry-level fork that comes on the Fire Mountain would be plenty good enough for my purpose.

So I’m now deliberating between the Talon 2 and the Fire Mountain. It really boils down to this:
Altus drivetrain + XCR fork + tapered head tube
vs.
Deore drivetrain + SCM fork + double crank

The Kona shop is brand new, so I have much more experience (all good) with the Giant shop. But I’m leaning toward the Kona bike mainly because the XCR has a damping adjustment. Wasn’t able to ride the Fire Mountain today, as they won’t be in until next week. Not sure how much an in-town test-ride of a mountain bike will tell me about the effectiveness of the rebound adjuster, but it should at least help.