You can usually safely refurbish diamond cut alloys twice without compromising their structural integrity, so it should be OK to get your Austin’s done again if they’ve only been refurbished once. However, because the machined face of the wheel doesn’t provide a particularly good key for the clear lacquer coating to adhere to, there’s a good chance they will suffer white worm again at some point in the future - probably in around a. couple of years time, or possibly sooner.
If I was considering buying an alternative set of wheels, I’d be looking for something with a more durable finish than diamond cut. A set of replica Austin’s will almost certainly succumb to white worm - probably in 18-24 months or less. I’d look for something with a painted / powder coated finish. If you’re considering BBS, they are a very good quality wheel, but even with BBS alloys, I’d avoid anything described as machined, polished or diamond cut as essentially they’d be diamond cut, so won’t have good durability, especially if they’re on a car all year round that’s used as a daily driver.
As for the quality of alloys from CMWheels; forum members over on VWROC that’ve bought Pretoria replicate have been generally happy with them, and I’ve not read of any instances of those wheels cracking or buckling (the OEM Pretoria’s are prone to do this if they’re subjected to impacts from large potholes and other similar road imperfections).