Re: Thoughts on this item?
I would go with the big 2ch rack unit (or the old one with the gold faceplate):
Yes, it will cost you more. But I suspect that's essentially a Tube MP with a USB jack. The big 2u pre (and the Pro Channel, a one-channel 2ru device) are different animals entirely. I just saw a Digital MPA for $250 on CL around here, and I suspect that would be give-or-take the going rate.
The ART Tube MP just... well, isn't that good. IMO, it's not as good as what you already have; the Focusrite pres are quite decent.
The big rackthing, that's on the list of best cheap preamps. (The Pro VLA tube compressor is nice too.) I have one (the older gold faceplate version); I have NOS Mullard 12AT7s in mine, it sends 300v to the tubes, has variable impedance, high pass filter, insert points (I use a FMR RNLA for this on vox and bass), Burr-Brown opamps, SPIDF out and decent converters too... It sounds good. Like, good good. It's a killer DI for synths and bass, and you can overdrive it nicely too. Yes, I'm talking you into swinging more for something significantly better.
At the end of the day though, I suppose it depends on what you need. Those are two preamps for cheap. I wouldn't expect much given their apparent origin. If you want to add a channel or two, there are options.
That being said, as both of us like to indulge in the lo-fi, cheap-and-nasty is a viable option. (And depending on how it's rigged up, you could potentially just get "clean" out of it.
So yeah, my instinct is to spring for something nicer, but depending on your application it may not matter.