I can understand your point, but if B&M manage to do enough research into it, work out how to increase throughput and speed up loading and I think it'll work. Just look at Thirteen for example. John Wardley worked with Intamin to make sure that the throughput of the ride was as high as possible and everyone has been amazed by how quick it is at eating up the queue lines. I'm pretty sure he'll be wanting to get the same out of this project (He's confirmed that he is working on it).
Also, when Arrow built X, it was very very half arsed, there was no real thought into the layout, into the harness' and into the overall ride. B&M seem to be planning this out well and if what they say on Screamscape is true about them testing it out at Gardaland, it could be one really amazing project. Now, the only 4D ride i've been on is Inferno at Terra Mitica. I have to say I loved every second of it. If B&M can pull it off, i'm sure it'll be better than how the other companies have done it. A lot smoother too I would wager.