I had owned a Feathercraft Baylee for a couple years now and have put lots of miles on it. (I am too lazy to write something from scratch, so I copy/pasted this from when someone else asked me about the Baylee vs. Alpacka.)
For me, doing a lot of first descents, the ability to hop in and out easily is a huge convenience and safety feature.
I haven’t run any big whitewater in an Alpacka myself, but from rafting with a friend in the new WW Alpacka, I outperformed him in almost every way. He was constantly worried about keeping square to the current in stuff than I was running backwards, sideways and half asleep. The rounder edges make it more forgiving. The Baylee is more comfortable and you sit almost 6 inches higher, so you can see over your pack better. It also is warmer (because the floor insulates you from the cold water) and more durable. The welded seams are awesome as are the Halkey-Roberts valves. If you use a pump you can inflate it rock hard. Combined with the inflatable floor, the raft in way stiffer than an Alpacka.
The Alpacka is a little faster on flat water, as the self-bailing holes create a little more drag. This also makes the current grab the boat a little more, which is better in some cases and worse in others. I just have a ring around the outside for my floor so it is faster than the ones with all the holes and slides over logs and rocks better. It still bails nearly instantly.
The Baylee would be harder to roll than an Alpacka (because you sit higher) but I haven’t found any need to roll yet. I can fall out and be back in faster than most people can roll. In real world situations (with a large pack in boulder lader whitewater) most paddlers will end up ejecting anyways. That said, the NRS thighstraps that I have are awesome (if a bit heavy) and it takes a lots to capsize the boat. You sit more in the middle in the Baylee and it is longer, so I have never gone over backwards, even in 7’ plus standing waves.
The Baylee 1 is bigger than even the Denali Llama, so the Bolder is huge, but then you could put your pack behind you if you want. I would get get a Bolder if cost wasn’t an issue and I wanted to carry lots of stuff. You’d float even higher and could do really big water.
Bottom line is, if you don’t mind the extra weight and bulk, I think the Feathercrafts are much better for river running.
Also there is a self-bailer on Ebay right now for $1200.