I use the PODxt for recording, and can say confidently that the tube screamer there sounds very much like the boss SD-1, which I also own. I've done direct comparisons, and the difference is quite subtle.
I use to record with the tubescreamer all the time, but not on my recent stuff. In terms of getting a good tone out of it, I can pass along some advice from Piet Sielck (Iron Savior, Savage Circus) who uses it, along with a POD 2.0, on his guitar work. To avoid fizzyness he keeps the drive at 0% and just plays around with the gain and tone dials, and takes out some frequencies around 15k.