Well, speed is not directly related to your kayak being inflatable. Instead, the speed of your kayak depends on the profile and most important length and width of your kayak. Inflatable kayaks with a wide cabin and bottom are slower than hard-shell kayaks. But, you can also get inflatable kayaks with a thin cabin. However, you need to master it first if you want to go straight away. Stability is already exceptional as these kayaks feature a wide and flat bottom.