30m (3 bar) basically means splash-proof, not even your stated 1m (activity while submerged, I suppose). Like, 30m is IPX4-5, 50m is IPX6 (very rough equivalence), so 30m is the barest minimum expected from a watch.

I wouldn't care so much about WR for a round Pebble, which I'd wear on nicer occasions. I would care more about WR for a watch that I'd wear at the beach or pool, as a way of getting notifications when not carrying my phone.

But screws might add thickness/weight to the watch, compared to glue.