We had the chance to put one of the premium record flattening machines, the ORB DF-01i,  through it paces last weekend, and the results are pretty darn impressive!
Having recently received a brand-new, sealed record from eBay's "importcds" (their service is terrible by the way - good luck getting replacements or even an email acknowledgement!), I decided this would be an excellent guinea pig for the task. The process takes four hours - two hours heating followed by two hours cooling (sometimes additional time may be required depending on how bad the record is).
Have a look at the video for a before and after. And no, the actual grooves are not damaged throughout the process, however my process is to clean both BEFORE and AFTER the flattening process. We hope to add this service in the coming months.