As long as it is faster than gitlab itself, sure. Every time I go to the hosted gitlab, I cringe. I like the product but the whole thing is sooo slow. First, 5 seconds wasted to "check if my browser supports gitlab", then the lag on every click. Hopefully your heroku will have a better experience than your gitlab.

Why should I care? I click sign in button, which takes me to https://gitlab.com/users/sign_in and I see the message. Who cares where it comes from.