There's no real issue with changing interfaces, I do this all the time between the 2 shown in my signature.
As long as both interfaces and versions of Sonar are using the same clock rate.
My self I stick with 44.1/24 for this and have never had issues.
Only noticeable is the screen size.
You may have to re assign inputs, no big deal. Outputs will stay on 1/2.
I will add that your Lexicon is a trouble maker with not very good drivers according to a few threads that have been around here. So if you experience any driver issues it's no surprise.