Hi Paul.
40 amp esc's sounds a bit on the "light" side, you could be running them on their top line. It may benefit from 60 amp units, better to have over capacity on the controller, rather than at max all the time.
I have one of the older types, and yes its fine when its running right, but once one of the grub screws slips and the gearing goes out of sync, you can kiss goodbye to 2 props in an instant [ha ha].
i do prefer it to the newer one, but have driven the "evo" and it still misbehaves same as my older one, once it hits bow wash or a bit of choppy water.
once you get the hang of avoiding such trivial things in the water you sail on, you can still get plenty of fun out of it.
Weight is always a big thing with these craft, too much and it wont get up on the plane and allow the props to do their stuff, same goes for the actual "balance" of the boat too, you could always try a bit of experimenting with battery position, even a few millimeters fore/aft, could make a difference, its a lot of trial and error,but worth it in the end, as i found that for choppy water, battery further forward was better, it kept the bows down but move it back 10mm for "mill pond" and it was on the plane as soon as it left the bank.