Which is fine. You're playing an MMO not a turn based RPG. You can't expect everyone on the server to have to wait 5 minutes while you activate your summon.
The fact that Demi-B is mostly passive, you don't get a pet action bar, you get a single active skill and the rest of him is merely just reacting to your natural spell slinging, makes it essentially feel like a one and done spell. Just one that has continuous barrage of damage over a short period of time as opposed to 1) Being an exact copy of single player RPG FF incarnations which wouldn't work in an MMO or 2) Being a crappy Egi that is active at all times and is a glorified DoT when they bother to actually do something useful for a change.
Is something that can be worked on.
A combination of design choices and visual effects settings can mitigate the negative impact for having such large entities being summoned in during Raid content.
Like for example, does Bahamut have to be near the ground? Could he not be flying overhead some distance?
Though, he has much less movement to handle.
This also has more lenience because Demi-Bahamut only has a single activated skill.
But in the end, Demi-Bahamut shows an example of an MMO capable Summon with a scale comparable to that of the iconic job.
Is it perfect? No, it has some kinks to work out.
Is it better than Egi's? Oh yeah, by a factor of magnitudes. Egi's are complete trash. Demi only has a couple of issues to sort out (Size vs visibility of others and some more AI work)
Of course, you'd never be able to have Bahamut to scale though... Given his hand was an entire battle arena for Twintania with room to spare...
