Speedy Boarding isn't a great product.....not because it doesn't work (it does work nearly all the time) but because it's just not worth it IMO.
Certainly all Easyjet base airports have speedy boarding off to a fine art and so do most other stations. Apart from one or two places, the complaints about bussing are unfounded as it's usually a speedy boarders bus or speedy boarders are placed at the front and just the front doors are used initially.
Where speedy boarding does fail, as someone else has mentioned, it's usually down to one or two idiots in the main queue who don't grasp the concept or who resent the fact that they aren't first. That said, from my experience, it is usually orderly.
Unalloacted seating is still being reviewed and as Easyjet continues to seek to "add value" then there is a very real possibility that allocated seating will be introduced. Having worked for an alloacted seating carrier before, it won't mean that everyone will be happy with where they are sat but it's what many passengers want.