Welcome to the macProVideo forums!
I've no experience with the UA-25, but notice you have an "Advanced switch" on it which switches to 44.1Khz only.
About your question, are you talking about hardware settings, or Logic's sample rate settings?
All Audio interfaces I've used have been controlled by the sample rate of the application (i.e. Logic). So when changing sample rates in Logic the audio interface automatically adjusts. Is this not the case when using the UA-25?
If you mean Logic's sample rate settings, then recording, composing, mixing in 48 is fine, then when you've completed the mix, bounce it down to a single audio file and adjust th sample rate in the Bounce dialogue window. When you bounce from a higher sample rate to a lower one make sure to choose "Dither" as well.