It's not "in" Mycelium but on a paper wallet, so no worries there.
Is it a paper wallet created by Mycelium, the "Single Address wallet" where you write down 15 letters after printing it?
In a nutshell, you're saying that Mycelium is perfectly capable of handling this transaction and that it is a perfectly viable option.
I've never tried large transactions on mobile myself, so it's only an assumption.
Again, I don't care if it costs me $3K in transaction fees as long as it is a solid option.
I wouldn't call it
solid: how secure is your phone? Are you willing to
risk a life-changing transaction? Chances are it will just be fine and arrive at the right destination address, but are you willing to risk even a (say) 1% chance your phone is compromised and your funds disappear?
The great benefit of signing offline is removing this risk completely. But you'll need to make sure you know what you're doing.