I reckon the Czech Gumotex rubber factory in Břeclav make the best value proper IKs in Europe (in North America they’re branded as Innovas). All you have to do is pick the best one for your needs.
In 2011 they stopped selling the Sunny Mk3 in Europe (it continues as an Innova for the US for the moment). The 25cm longer but near identical Solar 410C took its place elsewhere. Compared to some IKs, Gumotex are simple, robust and gimmick free, and over the years the design has improved: better skeg fitment and material, better removable seats, lighter material options while keeping PRVs in the floors. Better valves, a new softer and lighter Nitrilon, and now with fitted or removable decked boats.
The sporty Safari, the partly discontinued Sunny, the 410C as well as the Swings and versatile Seawave are all great boats and the Twists are very light. Some might add the old, semi-decked Helios 1 and 2 to that list as well. I haven’t owned or tried every Gumotex IK mentioned here, but in all cases know people who do- or have. The video below shows what sort of whitewater fun you can have with Gumotex IKs and even canoes.
Gumotex IKs are what I call ‘tubeless’ IKs (this definition has since been adopted by some resellers). There’s more here but in short this is the European way of making IKs: simply gluing all the sections into a sealed inflatable vessel. It’s more expensive but has advantages over the bladder ‘inner tube’ boats more common in the US.
Most Gumotex IKs are made out of Nitrilon, their version of DuPont’s hypalon: the original tough, synthetic rubber coated fabric as used on white water rafts that lasts forever but has now been superseded by similar but lighter fabrics.
You might even say that full-coat Nitrilon over a bit OTT so a few years ago Gumotex introduced LitePack (or Nitrilon Lite) boats like the Twist or Swing EX (in the US), with the rubber coating only on the outside. It saved weight but the boats won’t be as durable. Since then Hevealon fabric has been introduced on the Swings but I’ve not seen it close up. It could be a development of the not so popular LitePack. As mentioned the current Nitrilon (as on my Seawave) feels much more like a thick version of the glossy TPU-coated fabric you get on Alpackas, than the older, less shiny and stiffer stuff. Maybe not as tough but I bet it’s lighter.
One thing you should know with Gumboats is that all except the new Seawave (and the Ks) are rated at 0.2 bar or 2.9psi, something for which a Bravo foot pump (left) is fine. This is better pressure than many other IKs but not like the 0.3 bar boats from Incept and Grabner. I’ve read of Gumboaters running more than the recommended pressure in the side tubes to make the boats stiffer and more responsive. I suspect they could take it as long as they don’t get too hot out of the water. Running at the recommended pressure can mean that when a boat gets over 3.5m long – like the 410C or the Seawave – it will flex in the swell or rough water. This was a nuisance with my Sunny in roughish seas; it swamped over the sides, but at least the optional deck on the Seawave will limit this. But even on flat water, long boat flexing can mean reduced speeds if you’re heavy like me, and bend the boat. Apart from going on a diet, I considered various ideas to fix that, but in the end settled on a Grabner Amigo, a basic boat which can be described as a ‘high pressure’ 410C. Solid as a brick; no flex at all, but expensive. Since then I sold the Amigo as I was doing more sea paddling where a bit more speed helps. I now have a Seawave which I have adapted in various ways, including running over-pressure side tubes with added PRVs.