I have no problems with Fallen playing as infected, I'd kick his @ss like I did with other admins/vips, инженер included
Jokes aside, as a l4d2 veteran, I'd find it a bit more challenging, but Im not always in the mood to grind more than I want.
One more thing, servers are "COOP", players (Im mostly talking about weaker ones, who are still learning) are choosing this mode for a reason.
Therefore I think this should only be allowed in games with more than 10 players, If its allowed. The game gets hard enough for non vips anyways. Toss in few white chargers and the level is probably done.
Servers should be focused on, or at least, everyone trying to have some fun. If someone is bored and wants to change the style of gameplay, maybe its for the better they go on a different server? Or play something else? Rather than ruining someones day.
I hope I read all the above correctly as I dont speak Russian or Ukrainian.