Yes. 
[seriously I wrote a long post about this just a week or 2 ago as someone else for some reason puts TIFFs into GS and even uploads them to the GS image server [which thankfully converts them to jpegs, since TIFFs are not viewable inline by web browsers]. Doing the conversion ahead of time saves bandwidth for the transfer to whatever image service you use, plus also helps customers see the images faster.
I’ll find the thread and link it in just one second to this message…