>>65604765
Yeah I'd say they're worth it, especially since I got this one on sale for $350. It's supposedly their middle of the line (or second from best, the Z2 Force being their flagship), but I haven't really encountered any bottlenecks or anything yet. I haven't done a huge stress test on it yet though. From what I read, the Snapdagon 626 SoC is pretty good and seems to be able to do everything I want, the Z2 Force has a Snapdragon 835, which is better in every area than the 626, but it doesn't seem like all that much. Imo it wasn't worth the extra $200 to get the Z2 Force over the Z2 Play when I got it on sale. Right now the difference is only $100 and that might be worth it if you're sold on one of those phones. The Force is $500 right now for some reason.
But to answer your question concerning lasting, I wouldn't doubt this phone will last the time frame you outlined software wise. These can be unlocked too. I have an unlocked bootloader on this thing right now. Side note: I was kind of disappointed in the development scene of this phone. I shouldn't expect a Nexus 4 or Nexus 5 tier development scene, but I'm still kinda disappointed that there aren't more than only on or two custom ROMs for this. You'd think it would be a prime target for development since the manufacturer actually is A-okay with you unlocking the bootloader, though I dunno if the Moto mods would work with a custom ROM. Anyway, software should be good for the foreseeable future. Moto's stock rom is pretty lightweight with only the Moto mods manager and a small Moto options menu in the settings that I never use.