I'm only a beginner to intermediate paddler but I am keen. I bought a really cheap, battered, mistreated Stealth ski, (South African brand) for my son to try & get him into the sport.
I couldn't find any info on a Stealth Mark 7 so I don't even know if it is the same brand.
My experience with that one Stealth ski was that it was very flat bottomed & that you sat up high. It was not something that my son or I could really make friends with. It was just OK if you had nothing else. Plenty of primary stability but secondary felt funny to me.
The suggestion to try out a number of skis is a good one. You might think you'd be happy with one thing until you try something else.
If it is the South African brand, Stealth, I don't think that they make surfskis anymore. They focus on fishing skis. The Aussie ditributor took care of his customers but surfskis are not what they focus on & has been a while since they made them so unless you are happy with it & it is a real bargain, I don't know that it would be what you are after.
Surfski design has come a long way. I started with a cheap 1st generation Epic V10 Sport & now paddle a V9. The V9 is WAY more stable & more fun in waves for a mug punter like myself.