You're going at the problem from the wrong side. This won't balance things. It will just give more people overpowered weapons, and only if they know the commands to get them. Noobs do not know about /holiday eng.
The problem is as you stated it. Snipers are waaay overpowered. They used to be somewhat useless at long distances, before lagcomp came along. Back then, I felt like people became VIP for the chainsaw and modding capabilities. Now, it seems like the real reason to donate is the sniper, and the previously coveted features are now just bonuses. It's my belief that snipers were originally added because while they were good at long distance shooting, they sucked against moving targets at a distance, so they weren't overpowered. ...then lagcomp came along, and suddenly every VIP had the ultimate weapon. Perfect accuracy, range farther than people can even see you, and best of all, they work fine on moving targets. Tenshi didn't bother to balance it because he had entered his "fuck everyone else as long as I can abuse the overpowered capability" era.
Personally, I have disliked this ever since lagcomp appeared. The game for me changed from "run away from the pack of people right behind me" to "run away from the person with the sniper rifle, then from the pack". Anyone with a brain and reasonable mouse skills can easily shoot you from extremely long distances, as long as it's line of sight, and it takes down a fuckton of health. As a bonus, it also annoyingly stuns you so you get hit even more. There isn't any disadvantage from a distance. It's arguably the most overpowered weapon in the server, and a good chunk of the players have it, leaving the non-VIPs fucked.
I think the solution to the overpowered VIP issue is to reduce the
weapon skill for the sniper. It will probably still be overpowered, but at least it's a start that will help, and let the VIPs keep their snipers. Then we'll see if this is still a problem.