The UX series are fine.
They're not stellar, but they're fine.
The thing about modern DACs [Digital Audio Converters] is there really isn't a huge amount of difference any more between the bottom end & top end.
Just so long as you don't over-compress, or use heavy EQ (also don't record the reverb, because that will in fact suck, big time ;-)
If you're recording electric guitar, then you're going to either have to do it clean, or pick an amp model that will still sound good at the mix. The UX is capable of that, but don't go overboard with any type of effect that could better be added later.
Think in terms of 'pedals before the amp' & leave out anything you would consider a 'studio effect'.
If you're going to be using a mic on anything, then your bigger concern would be the quality of the mic itself & the room sound of your studio.
I have a UX2 these days [budget constraints] but I still have my mic case from when budget wasn't so much an issue & I can attest that something like a Neumann U87 or a B&K 4006 through a UX is really almost indistinguishable from one through a 'good' preamp. By the time it's in a mix it would take an extremely good pair of ears to spot it.
I record guitars through it in the same fashion, though most times I will play through clean & use something like Guitar Rig to provide the amp. This gives me the opportunity to change the amp settings at any time right up to the mix.
That may be harder to do if both of you [recordist & mixer] don't have the same software.
One thing I didn't consider was keyboards...
I'd say, so long as every sound is recorded individually, again leaving out any 'studio effects' like reverb etc, then you should be fine.
At all times, watch your levels - don't hit the top, but don't waste 16dB of headroom 'just in case'. Don't use the UX compressor much, it's OK for a very gentle smoothing on the way in, but nothing like a 'real' one - you would be far better off leaving that to the mix engineer.
Before you start, check what the mix engineer wants for stems - WAV, AIF etc, bit depth, frequency. It's no good you doing the whole thing at 16-bit 48k if he wants 24bit 44.1 (which he should, at minimum;-) If he needs anything more than 24-bit 88.2, you might struggle, as that's what those DACs will stretch to [48/96k is no good for 'CD audio' so don't use that].
Perhaps above all... don't try to make your initial tracking sound "like a record".
That is not the recordist's task. There are two more stages to go through before it will sound like a record - mix & master.