It works well for me, no surprises. I don't mind paying to have my stuff serviced every other year. It is peace of mind to me. I would probably have them serviced in that interval anyway. So to me it is not that big a deal. I try to take care of everything I have my scuba gear is no exception. To me $75-$100 every 2 years is not a show stopper, $75-$100 is mere pennies/day over a 2 year period and worth the peace of mind it gives me. I'm OK with it and I am pretty sure I am not alone. I spend a lot of money when I go on trips and I really don't wanna screw around trying to repair a regulator when I am on vacation. I test the reg after service and before I go on trips. The manufacturer says to service it every other year, I am ok with that. If they want to offer free parts...I am good with that too. I have a good place to have my stuff serviced and they do it quickly at a reasonable price. Evidently, if I am to believe what I read here, that is not the norm. Guess I am just lucky.
Typically the free parts programs have required annual service, but lately a few of the manufacturers are switching to every two years. It's still a scam, and here's why:
First, for 'average' recreational use, meaning 50 dives/year or less, regulators that are well cared for can easily go far longer than 2 years between service; maybe 5 years or more. About the only thing likely to need some attention might be the 2nd stage seat, and that's likely just an adjustment. Of course, not everyone cares for their regulator well.
Second, the true cost for these 'parts' is mere pennies. Maybe a dozen o-rings that are certainly less than a nickel each at wholesale, and a couple of plastic seats that are likewise very inexpensive to produce and inventory.
A big part of the scam is the gall that regulator companies have in charging $20-30 for the rebuild kits which consist of these parts. This artificially inflates the value of the 'free' parts. Once you find low-cost sources for the o-rings and seats, parts cost for rebuilding many regulators is only a couple of dollars. Some 2nd stages are far less.
What would be 'reasonable' or 'fair' pricing for regulator service would be about $5 for a parts kit, maybe $25-35 in labor, per stage, as needed. For most recreational divers this would be once every several years.