Here is a great write up from Chris Payne over at Payne Outdoors on the difference between kayak stability versus standability:
This article really highlighted the differences between my Ocean Kayak Trident 13 and my Pescador Pilot 12. I found the Trident to be very stable and it served me well for my first few years of kayak fishing. The only gripe I had with the Trident was that I was not able to stand up and cast and I knew that would be on the “must have” list of my next kayak.
One problem I have with kayaks that are “standable” is that they are usually not as nice to paddle. Wider means slower and typically the standable kayaks start at 33” wide. My Trident was 29” wide and a dream to paddle, the Pilot is 34” wide and I only paddle it far enough to put down the pedal drive, it sucks to paddle by comparison.
So if you are set on a standable kayak just know what to expect. Long distance touring is still achievable but the pace will be slower than a kayak with a slimmer waistline. If you want the best of both worlds I think a standable kayak is better with a pedal drive.