I was checking on starboard websites.
Is it possible that you are riding the 2013 82L...and that board is 58.5?
The 79L 2015 is 57.5 and that's the same width as the 74Quad 2013 and JP 83L with closely the same length.
Width plays a big role in feeling, I had some spins on some starboard in 2012-13 and they were feeling easily 5L bigger than what I was used to ride for the same L.
It seems that they did reduce the width on their quad in 2014-15 or adjust some L on their board. 82 us now 84 and the 87 is now 89...but shorter and thicker...so the 79 would feel way smaller under foot to my opinion than your 82, however to come back to the original discussion. Is 79L is too small for you. It's your feeling that count...however if you stick in starboard and it's still the same feeling as before, add at least 5L to your board volume...so at 82 you are easily at 87....Quatro or JP...and that is pretty close to what they were suggesting to have.