Don't forget to share of few photos of Zambesi tigerfish to scare the locals here
and remind them how nice and peaceful pike really are!!!
It sound like you know your onions... even the lakes here can get a pretty big wave on them, and Derg has the added problem of the mountains creating nasty weather fast. Like Corrib Mask and Conn. So you need a decent high gunnel if you want to venture out in changeable conditions. Avoid aluminium boats - I know they are popular in Africa and especially on rocky rivers... but I was out in one in the sea recently and its so light it bobbed around like a cork in an unremarkable swell, just awful. Sounds great. Isn't. Quite a few now have compartments in the keel area for ballast (often lead) which might improve things but I still would not recommend it...
At or under 16 foot or so, you cant go wrong with the Orkney Strikeliners (O'Sullivan Marine do similar versions) are probably your best bet. The Coastliner at 14 foot is a bit small, maybe ok in the Shannon Estuary on quiet days, but the longer boats offer a deep V hull, that planes on a relatively small engine, they tend to be beamy design wise and so are very stable and therefore good in choppy conditions and are tough as nails.
At 16 up to 18 foot you're into a whole different price category, especially around the engines, but you cant look past a Warrior 165 (or bigger) as being the pick of the crop. Warriors needs a big engine, but they can take you properly offshore. Big fish off wrecks, even tuna are as possibility if you haul it down to Kerry. Again there are remarkably similar designs to the Warrior out there where you avoid the brand premium if buying new... just pack the spare engine cos you're not rowing them home!
Loop Head and the Shannon estuary still has good fishing, with Tope, several species of Ray and Bull Huss amongst the bigger predators targeted by boat anglers. It might not be what it was 30 years ago (who or what is?) but its probably a damn sight better than the headcount and quality of fishing available in Lough Derg...
And the Giant Bluefin Tuna run up the Shannon in the autumn as far up as Foynes according to the satellite tracking if you fancy BEING TOWED !
There is also an Australian kayaker here who is/was threatening to look for porgies and blues under Loop Head, not sure if he's done anything, he might have moved on... but he has video up of taking in whalers and pointers from beaches near Perth. Do a search (top right hand side ).
Hope this helps... don't forget to post some reports!