Shane said . . .
You could go either way but I would lean you towards the 79 especially as a learning boat I would go with the larger design because it will take care of you a little more.
Thanks, Shane. I'm pretty happy to go with the 79 - it seems to me its a better match with my weight, and it gives me a bit of scope to carry some kit, if I want to. And if I ever get good enough to really think its one or two inches longer than I can use, I'll maybe be ready to get a Hefe, or whatever
Thanks to everyone for their input.