155 is easier for crew to handle, so in short races you can get a few seconds each tack, just because they have it working well faster. That is if indeed they are fast enough to get it in without the need for skirting and the driver is working with them to that end.
Problem with the 163 is that it really likes the 1400 lbs in wind over 14.
and it also likes more of an athlete in the trimming positions as that becomes a mandatory two man job. the Vee Jays use 155 on rollers.
