The reason for a non-GPS system at the alternate is that if there is a
GPS RAIM outage it probably affects your alternate as well. Hence a
different system. That suggests that ANY GPS navigation is not
allowed. Of course if the original GPS outage clears then you should
be fine. My opinion of course.

I also believe that this restrction is not in place if you use WAAS
because WAAS provides the required integrity.

Ron Lee