My first boat was a 2.6m inflatable with 4hp yamaha I used to fish the mouth of the Manawatu river in NZ. Inflatables are incredibly stable and I used to stand 2 people and fish from it. Inflating and deflating can be a biatch and take a long time, I would invest in an electric pump or a really good hand pump.
Material its made from is really important, the cheap ones are just glorified pool toys and will become useless after a few years. The good ones like the zodiacs are quite pricy and can still be quite bulky when deflated.
If its only a short distance they need to swim, perhaps an inflatable kayak of some kind would be more suitable?