I have an unsealed Sugino bottom bracket with loose bearings. I ride the bike in Seattle in the wet but I do dry my bike off after rainy rides.
If you use thick marine type grease (I use Lucas red) and just periodically check your bottom bracket for dirt/water, you'll have a lot better luck with catching any potential issues. Inspecting your bottom bracket can be done quickly with the right tools...maybe it's the masochist in me but I find it fun being able to visually check everything/repack the bearings.
Only downside is that you can wear the taper on your cranks over time from pulling them off/re-installing them.
You will need some tools to do it but like I said before, I find it enjoyable pulling everything apart the non-drive-side, checking the bearings (possibly having to repack them), tightening back up, checking the spindle play, loosening/tightening until you get that perfect spindle feel that doesn't have excess play but still spins smoothly.
I'm also someone that recently converted their threadless fork/stem to threaded/quill so I might not be the right person to give advice.