i'd keep them since you already maxed out their breaks.... plus they do somewhat help until you get better eidolons from events since they're one of the better SR eidolons...
also, break limit doesn't affect exp as far as I know, only leveling them. but it's diminishing returns anyway so you're better off not using them as fodder unless you got a + value you want to transfer from them
on sundays like today where the gem quest is open all day.... that's not really an issue
plus it's good exp for sunday while the 30 min one that pops up is strictly gems and at least double the gem rate compared to sunday...
either way, even newer players can rack up gems when they can get their hands on the gem quests.... especially like right now where there's no event going on
even still, 10k gems is very easy to get...
events (especially raid ones) even hand out far more than that if you can do them well enough.
at most, gacha will consume 110,000 gems daily. another 10k isn't hard if you already grinded out that many to pull daily. as for accessories, if you're still using the SR eidolons, you're not ready for those yet
I have like four pages of Disasters in my inventory. If I had LMBd them, they'd be in three pages.
And cost me 600k more Gems.
Spending Gems for the sake of spending Gems isn't worth it. Until I manage to amass over 2m stockpile, I'm not wasting any Gems. Currently, as a EU player, I'm pretty much hovering +-0 Gems income a week. This includes events, as I can't do enough of Gem Quests.