At this stage Whitey I would keep what you have got. Your 7'11" Evoke is so similar to my JP Widebody 8'2" But your Evoke is a higher volume board at 131 Litres compared to the JP 124 Litres but you are about 15 to 18 kilos heavier than me so that just about makes us twins when riding our boards. Lol!!!!!
My JP is so stable and yes I could throw it around if wanted. But since bought a better performance board, a Sunova Soul 8'3" which is soooo much lighter to throw around & I believe is easier to control & catch waves due to its lightness. But your Evoke is carbon so might be just as light, but might not be as fast due to the Sunova being less in width. And yes, I noticed the big increase in speed.
But my JP Wide is great in mushy waves too, except I would have liked more rocker or nose kick in the steeper waves.
So since I have tried & purchased a Coreban Hyper to assist my balance, paddle & late take off practise, so when I return to my Sunova & JP I would have the confidence in more critical surf. Lol! Well I hope so. Lol!
But what I have noticed with the Hyper, it will bog down when the waves get fatter & the board slows & I think because of its excessive rocker. But I want this board mainly for those steep sucky waves that will generate speed very quick by the time you do that bottom turn.
So going back to you wanting a board for those mushy waves, I think the Bam Bam at that volume would be too much work & boggy due to its volume to your weight. But its rocker may help you out being what I think is a little less compared to the Hyper. Understanding that I haven't ridden or viewed a Bam Bam in reality.
But. the Bam Bam will help in balance & paddle practise. And if it has a more pronounced rocker or nose kick then it will help with late take offs too as the Hyper will do for me.
So in my opinion, if I were you, keep the Evoke for an all rounder especially for your average surf & mushy days. And look for a higher performance board with a little less width for average to bigger surf.
At your weight & affordability. I would get a Vex Profusion Carbon at probably 8ft or maybe the next size up. Which I nearly chose except the volume was too high. But if I was your weight I would have snapped it up. They look the goods & heaps cheaper right now too. With a more pronounced rocker. I think that would make your quiver.
The Bam Bam for fun, paddle & balance practise at your weight.
But that is my opinion at 55 years of age, 78 kgs plus weight & being just an average surfer wishing to be more aggressive in wave shredding. Lol!