Yes this option now exists, and I use it too, but this should be the default. Losing time/effort is way worse (especially when the program doesn't say you are going to lose all your work) ..
SEQ should be the default, plain and simple. This has bit too many users in the butt.

If it Saves as a SEQ file as the default, I can later go back and edit it and save as BIAB file, with my choice on what it contains. But when I've worked for a couple hours and Save the file, only to Open it later and find I lost everything I did; that is unacceptable.

I'm a programmer; I would never allow this to happen if I knew about it.
The user thinks everything is fine, only to find out later they have an un-salvageable disaster.

Example:
I have a BiaB file I got just where I want it. I Open it in RB, record a guy I paid to come here and add parts .. then I hit Save.
Tomorrow everything I paid him for (and the performance) is lost.
It's avoidable .. with no real cost other than a few minutes saving the SEQ file back as a BiaB file later. The 'option' should be to change it to save BiaB files as Biab .. but the default should be the most loss-less, user-proof method; SEQ files.

If you can't tell, I feel strongly about this one.
Why make the defaults cause possible data loss to a new user? It makes no sense.


I do not work here, but the benefits are still awesome
Make your sound your own!