To continue playing devil's advocate, how do you know it breathes harshly? Have you compared it to anything else?
FWIW the experience on the diver end of the reg is largely determined by the 2nd stage. The 1st stage has to be in some poor shape to influence actual breathing experience. If you have a downstream 2nd, just upgrading to a balanced 2nd, or better downstream could make a difference.
In terms of freezing....well, that depends a lot of a lot of things, including you. I personally know 2 people that had their SP MK25/S600 freeze on them at ~100 feet in Cove 2. That's a bit disturbing. but it can happen. If you really want to avoid true freezing, not just free flow, you might consider a top end diaphragm reg, like the MK17, HOG, or the new Deep6. The reports on the Deep6 have been excellent. Piston regs in cold water are a little more prone to freezing.
Note - ANY top end reg can go wildly free flow under some circumstances. They are designed to put out LOTS of air and once they start it can take some specific steps to stop them.
Once you buy a reg, use it, then it comes to service time they kind of all end up in the same 'used' category. Not quite like used cars, but....there you go. They are chunks of metal, with O-rings, seats, and some fiddly little parts. Clean the metal, replace the O-rings, seats, and parts that need it and you are good to go again.
I'm NOT trying to talk you out of spending your money if you want to, and it sounds like you really want to. If so, have at it.
To Air is Human,
To Respire, Divine.