Do using a different offset wheel affect alignment if all else is equal?
Goggle search provides different views but the knowledge is among us.

So is using a set of winter wheels and summer wheels with different offsets
a good idea?

 

If your widths and offsets are close enough that both wheel sets fit without rubbing, than you will probably be OK by not getting an alignment between switches. Flat is flat. Going from a wider tire to a skinnier snow tire has less effect on alignment as long as that alignment is a good one.