Will I be sorry?
First off I wouldn't pay anybody $5000 for a paint job, that is just wack. My friend just had his DD painted at Macco and I think they did a real nice job.
Quality paint, like PPG, can cost over $2,000 just for paint and primer. Add labor and supplies, and $5k for a paint job isn't that much at all, not for quality work.
Maaco buys paint by the 50 gallon drum. It's not quality stuff, and it won't last. As far as the quality of their work, it depends completely on the employees at the one you visit. Some people have had luck doing their own bodywork and prep and having Maaco spray the primer and paint. But I've also heard horror stories about guys getting cars back with tape lines and paint on their windshields, bumpers, trim, etc.
Realistically, even if they do decent bodywork and spray it out well, the paint they use is not going to look good for the long term. I've seen cars shot with PPG paints look GREAT even at the 20+ year mark. With Maaco I would be surprised if it still looks good in 5. My Challenger, which was painted by a previous owner, no doubt at Maaco or somewhere similar, looked pretty good when I bought it. Within 18 months the clearcoat was peeling off, and at the 7 year mark now there's pretty much no clearcoat on it at all, and some of the paint is gone too.