I've been using a Sevylor Tahiti Ranger for the last couple of months and would rate it as more than a beach toy.
Last weekend a friend and I(he has one too) were on Loch Fyne(sea loch). On the way out there was a fair breeze(about 10knots max) blowing offshore and slightly from behind. The wind did catch the kayaks but would have had to be much stronger before there would have been any danger of not being able to paddle back to shore.(on Loch Lomond a few weeks before we were able to cross the loch at it's widest against a far stronger wind - coming back was a laugh
)
At Loch Fyne we ended up moving about 300m offshore to get out into steady wind. In at the coast the wind was unpredictable, gusting down valleys and round headlands and generaly just being a bit irritating.
On the way back the breeze had dropped to about about 3-5knots and travelling straight into it was plain sailing at an effortless 3mph(for 2 hours). Had the wind not dropped we planned to come out with it to a pick-up point round on the Mull of Kintyre but as it was getting back to the truck was a doddle.
The wee things were quite heavily loaded with 2 large rucksacks, a tent and assorted gubbins in each. There were other pals with us who were able to walk along the(very rugged) shore because we were transporting their gear for them. With a rucksack on traversing that stretch of shoreline is quite dangerous and exhausting.
Even with all that load the inflatables still felt stable.
As for rivers, we haven't got round to attacking any yet but it's on the cards. Sevylor inflatables are quite popular in whitewater circles, many adventure centres use them and I have no doubt that this one will give hours of mild whitewater frolicks.
The Ranger model has a protective cover made of heavy duty gortex-like material and I must admit I'd feel a little wary of running over rocks without it, but the "orange torpedo"(the standard one-man tahiti) has been shooting rapids around the world for decades so maybe they're tougher than I'm giving them credit for.
Another plus for the Ranger model are the two tracking fins built into the cover. Without them the kayak wants to wander around aimlessly and I believe a rudder is essential for open water use with the normal Tahitis.
Packed up the whole affair(including paddles and footpump) fits into a 70litre rucksack. There's no way I could carry it on my bike as I have a single seat unit which limits me to a 45litre pack. Without the cover it would probably fit and the orange torpedo would easily be transportable. The piccies I've seen of it packed up looked like about a 30litre pack. The poles for the paddle could maybe be tricky to as they'd be bouncing off your helmet unless positioned far enough back or bungied onto the bike.
The plasticwork for the paddle, the pump and repair kit would all fit into a tank bag no problem.
Weight would be fine. I've carried about climbing gear that weighed more.
Don't get me wrong. I'm not trying to make out that inflatables are as proficient as solid-hulled kayaks, they're not, not by a long shot - but for £180 and considering that I don't have any storage for a real canoe I'm well chuffed with the Ranger.
Josh