"Too little" depends on what you're doing. We have two dinghys: a 7-foot (no transom) and a 9 1/2 foot (RIB).
The 7-foot rolls up to a little bigger than a basketball (plus a ~18"x2' floorboard and a small transom-thingee), and will (sometimes...) plane with me and a 2HP. It and it's 27-pound motor are AWESOME for hauling around. It's also downright scary in any kind of chop or with any kind of weight, dogs
hate it, it's not stable enough to sit on the tube so my butt's always wet, etc. It's just generally a pretty sorry boat - but it fits in carry-on luggage, in the baggage area of a Supercub, in pretty much any locker, and my wife can easily handle it and it's motor.
The bigger dinghy is a a completely different boat: it's dry, safe, fast, and stable, even in big water
carrying a lot of weight. The extra 2 feet WAY more than "doubles the size." It's an awesome boat - but it's also a pain to deal with on deck
, we have fuel
cans everywhere, we have to use a halyard
or crane to move the boat or motor, we have to have wheels, it BARELY fits on the foredeck, etc.
My boat came with a 8.5' plywood
floor with a 4HP motor, which was the worst of both worlds - about the same weight as our current
"big" dinghy, about the same performance as our "little" dinghy, and a huge pain to get the floor in and out. It did roll up into a fairly unobtrusive package, but still big enough to need to live on the foredeck.
If you just want to go a couple miles in calm water
, the little 7-foot "inner tube with a floor" and a small motor would serve you well, and they are really great to stow and move around.
If you're going to be in any kind of rough water, get the biggest dinghy you can deal with. If you want to explore over longer distances, think about a RIB
and a bigger motor. We want to go where we want when we want, so we deal with a heavy motor, a big hunk of plastic in the way on the foredeck, lots of fuel cans, etc.
I generally dislike air floors, especially with larger motors, but if you need a "big" dinghy and don't have room for a rib
, that might be an acceptable compromise. It's where we were headed before we found our "big" RIB, which fits only because it has a folding transom and a combination of big tubes and a small hull
. You'll spend a lot of time digging sand out from under the floor, hoping that strange "sproing" thing doesn't ACTUALLY fold the boat in half like it always seems it's going to, and probably get to know the warranty folks (if you can find something that HAS a warranty).
If you don't know what you need, get something that's either disposable (eg, used PVC) or resaleable (major brand, common size hypalon) and see what happens. ALL dinghys are a compromise, you just have to decide what you need, and what you're willing to live with (or without).