GP5000s feel quite a lot different back to back with 4 Seasons, but 4 Seasons are still nice tires relatively. Roll well while still are sturdy and grippy. GP5000s feel like a race tire - whereas 4 Seasons don't.
I've not found pressure loss to be that bad (read: comparable to tubes) with copious amounts of sealant. I do have one tire that weeps from a tire plug-repaired puncture however...
This is with 28mm tires so pressure might be low enough to be ok.
I've got one on my steel vig and had zero issues with rain. Each to their own though and the king option would be more sturdy.