I love my solo plus, and have no concerns with the 0.51 cuben, I think that it is just fine for a shelter. However, if you think you would want the 0.7, I would say go for it, the weight difference is pretty minimal, and would indeed provide more durability.
They are taping them now, which would be the only mod I would ask for, so no reason for that now. If you plan to ever use this shelter for 2, or in a fair amount of rain, I would also suggest going with the beak. You could get by without it, but I like having mine there as a little extra reassurance. It's nice. I would suggest getting at least one strip of the single sided tape and keep it in your pack though, just in case you ever need to repair it, this will be your best option.
Anyway, if you want to read up on the solo plus some more, check out my write up & videos on my blog: