I have a SUB and love it. Only downsides to the layout blind that I can see, are climbing in and out, and you can't really see behind you. No real reason to be in a hurry to get out anyway (unless a 12 pounder is falling on you, then well, take it like a man), and not seeing behind you is worth being able to see them in front of you at a distance of feet. First time me and a couple friends tried them, I called the first pair of ducks too late, by the time we sat up my friend had to duck as he almost had a mid air collision with a nice mallard.
As said, stubble them up really good and they just vanish. I find them quite easy to shoot from, but angle them a bit, so assuming you are right handed, the geese will be coming slightly off your left side instead of off your toes, makes shooting a bit easier. I don't think the particular camo pattern is too important if you mud em and then use lots of stubble. Also make sure you stubble in with chaff from the field your hunting, don't go into a pee field with bright yellow whoop grass, (yes I've seen it done, and no it didn't work).
Features you really want from my experience are:
A full floor, if you don't have that you'll have everything full of dirt.
2 doors that split down the middle, that way you can sit up through them and they fall open, a single door is a pain to get open before you start shooting.
Stubble straps are essential for camoing in properly.
If you don't like looking through the screens on them, make sure you have a good camo face mask
Specific to the Sub, it can fold right down, and I do for storage, but it's nice if you can just leave it assembled, it fits easily the back of a short box truck with a tool box, as the foot bag folds up to shorten the overall length. I can actually fit two of them and some decoys in the back of my truck, without taking them down.
On any of them, in colder weather, an extra layer of insulation under the blind, or under the seat at least would probably be a good thing to keep the cold ground from getting to you, otherwise they cut the wind well, are quite comfortable, and the big trouble is staying awake. They are certainly the most comfortable way to goose hunt that I have tried.
If size of the SUB concerns you, I'm 6 foot and 220LB and I find it quite roomy, maybe a little cramped for calling, but I still manage.