This 'working out the kinks on itch before moving into Steam worked pretty well recently for the German devs of twin-stick Synthetik. I have like 60 hours or so in that.
The boon and bane of getting onto Steam is there your audience might zoom up a thousand-fold and a small dev team may have its hands full trying to respond to all the feedback at that scale. So if they can get this relatively polished on itch.io before its Steam release (or if they go into a Steam early access period), then that should be for the best.
I like Beacon's ideas enough to get it on itch yesterday (my first ever purchase here). :) I'm not very good at it but appreciate what it's trying to do and the general twin-stick shooter gameplay feels good.