Short version: I'm wearing Alteras with the Fusion and I pretty much like them.
My prior dry suits I've had attached vulcanized boots, Rock boots, Converse All-Stars, and wet boots.
My last suit was a CF200, which didn't have attached boots. I tried Rock boots with it (sole too wide for overall volume), and All-Stars (loved the secure feeling on the foot, but a PITA to get into). I eventually went to just wearing regular wet suit booties, great flexibility and fit.
So when I got the Fusion, I tried wet suit booties. Mistake - when you have lots of insulation under a bigger bootie, the fabric on the Fusion is slippery enough that they would slip off easily.
So I tried the Evo's and the Alteras. The Alteras are easy to get into and the fit into fins is really good. The downside is they don't feel as solid as I'd like at the top of the ankle, but despite this, they haven't tried to pop off either.
The Evo's do feel solid for me, but are way slower to put on. So, since I really hadn't had a problem with the Alteras, I went with convenience.
Vulcanized boots are great, but my prior experience was having to send the suit back to get the next-larger size installed when the chart-indicated size was way off. Once I did have the right size, they were warm and comfy and convenient. It was such a PITA to get them right, though.
Everyone's different. Some I'm sure would love to have vulcanized boots attached, and so would I if all I used the suit in was a single temperature water.
However I'm finding the Fusion to be far more versatile than I expected. I've spent a lot of time in warm water with it, and it's great when using a thin polypropylene sock under the suit and just pulling on my regular wet suit booties. Without all the cold water insulation this is very secure and seamless when transitioning between a 3mil wetsuit and the Fusion - same booties, fins, etc.
So, I'm not willing to give up the versatility I have now, by switching to attached vulcanized boots. Others that don't use the suit in such a varied way might opt for it.
Whew! Lots of talk there, I realized I didn't really come to a conclusion, but <shrugs> that's my experience so far. Versatility or convenience? Hmmm.
All the best, James