The problem with tracking a UAD2 is that it needs to come before the hardware WA2A to tame transients before being compressed by the optical. So that's out unless I do the 2nd half of the chain in-the-box.
My fear of buying a Klark, and I've asked some stores about this and they confirm it (although I have no personal experience with Klark) is that they have gone down hill in quality since having their stuff made in China. And for that price-point, but still using good components, it's HOW it's put together that is the weak point. (ie soldering, poorly glued large components, etc)
For example, in the same price range, but a little more, is the Warm Audio WA76, right? I ordered one used off Reverb: DOA. I ordered one new from a music store: 100v Cap broke loose in shipping and was rolling around. The company said it's supposed to be glued but it wasn't. So the manufacturer isn't even following the companies instructions. They inspect each unit in-house before shipping to stores. But I guess the 2nd shipping was too much for it. Point is: Not robust due to poor quality of manufacture. Hence my interest in going more expensive and quality-oriented than the Klark/Warm Audio range. So I chose the BAE 500C since I have a 500 Series Rack (Heritage Audio, 6 slot)
Also, at some point, these 2U units take up a LOT of space. I can get many into a 3U 500 Series enclosure, but there are some differences when you pair down to that size. A 500 series may not sound exactly like a 19" rack unit of the same company. You have to make compromises on component layout, type and size.
I bought the Lindell 1176 clone for my Lunchbox and am pretty happy, especially on acoustic guitar. It is NOT subtle, but sounds pretty "vintagy" when set up right. Also, it has a blend knob.