Based on your weight I would imagine that a 7'11" Spice will be super easy and stable for you. As for comparisons to a pro, I've tried an 8'2" Spice and it was much more stable than my 8'2" Pro.
I've had my 8'8" Spice in the "carbon" construction for over a year now. According to Dawn Patrol I've done 109 sessions and caught 1483 waves. Dawn Patrol also tells me that the total wave ridden distance is 64.4 kms and 4h34m of wave time. Sadly these stats are incomplete since my Apple Watch struggles to record beyond 3 hours on a charge due to its age and a tired battery. The Spice is a wave catching monster and I tend to average a wave every 6 minutes. The 8'8" is 140 litres and I was somewhere around 105 kgs last year without a wetsuit. I find it super stable even in challenging conditions and it works well in everything from mushy ankle biters to solid 8 foot. It's a fun and easy board to surf and is very forgiving but will carve nicely if you put it on rail.
The Spice was the exact board that I needed last year to take my sup surfing to new levels, but I have moved on now to an 8'2" Pro and a 7'10" Infinity Escape Pod. I haven't used my Spice since May because my aim was always to keep reducing the size and volume, but I don't want to get rid of it just yet and I kept it specifically for the big and woolly winter storms, when the conditions are too big for the Escape Pod twinnie and too rough for me to be comfortable on the Pro. The Pro wants bigger waves with more power and struggles to make it through sections on the smaller days.
The Spice will be a great board for you, but I would also look at the Infinity Escape Pod. It absolutely excels in the conditions that you've mentioned. You could even get one of the smaller models, considering your weight.
Here is my "review" of the Spice from last year
www.seabreeze.com.au/forums/Stand-Up-Paddle/Review/Starboard-Spice-8-8-Carbon-initial-thoughts