Using both SQLCE and SQLExpress

I have an app which currently uses SQLCE, and the schema is in a sdf. Now we want to allow it to connect to a SQLServerExpressEdition based on some mode. I have a couple of queries 1) Will the sqltolinq files (generated by sql metal) be the same for the both the databases. (Apart from the name etc) 2) Can we use the linq file generated for sdf, and extend it for the sqlExpress, and override any DB specific things there. Or is it not advisable to mix both of them ? ...