I personally don't like the idea of full time Demon because I always felt horrible for Golddust spending FOREVER to get that paint on to stand behind Stardust cutting a promo. Don't wanna see him get painted up for 2 hours for 8 minutes on Raw and watch nobody care about the paint.
Glad to see I'm not the only one who feels this way, I mostly don't want a full-time Demon because I know Finn's got to spend hours getting that paint.
That aside, I don't really like how WWE and Balor go about the Demon. Granted, the most I ever watched of WWE was their youtube clips of the segments I cared about, and it's been quite some time since I've bothered to do about that, but from the impressions I've got, not only does the Demon only appear very sporadically at seemingly random intervals, it kinda almost feels like that aspect of his characters is addressed as sporadically. Like, if the Demon's not going to be involved in the match, it's not addressed in the program. Which if that is the case, is something I severely disagree with from a character writing standpoint. I'm not saying it needs to be shoved down our throats every-time he shows up, but it should be involved in his character. I don't want to criticize too heavily if it's a misunderstanding from me not bothering to watch but rather than The Demon feeling like an aspect of Balor's character, it's more of a part of his moveset. Having this powerful alter-ego thing isn't woven into his regular character enough, unless Balor needs to set it up because he's about to go Demon on somebodies ass because it's his instant win option.
But that's nothing compared to my problems with how Balor handles it himself. I mean, he might as well be The Demon full-time if he's just going to the wrestle the exact same as both of them, minus the fact that he wins as Demon. I'm not saying he has to radically alter his moveset but the fact that his entrance features far different movement than his regular entrance, and then goes straight back to basically just wrestling as Balor is nothing more than a reminder of the miss potential in this gimmick. They do occasionally show the power of the Demon in rare spots, him no-selling Wyatt's stupid upside down spooky move is one of my favorite things ever, and they did let him powerbomb Bobby Lashley at Mania (though they had him struggle too much to do so, which I honestly thought weakened the Demon's aura) but ultimately, bell-to-bell it really never seems to matter whether Balor's wrestling as the Demon or not because he doesn't bother to inject any of the distinct personality the Demon displays in his entrance into the matches. Even if his moveset remains largely the same, just altering the psychology behind his movement would go a long way to make the Demon feel more effectively distinct. Feel more like a character than a gimmick.