A 1k to 3k drop in rpm is a pretty good hit especially if it falls out of the tq band. You must be playing on a high speed track with few 2nd or 3rd gear corners to be considering going to a 44 tooth rear.

Edit: What track you planning on running the H1 at? I was comfortable with the 16/46 at PIR Was easier to stay in the tq band in second on the tighter corners for me even though 5th gear topped out just prior to the front straight brake markers.