. . . and both of them probably only cost 50p to manufacture in the far east (and probably cost BT twice as much to purchase!!)
BT have to justify their massive monthly charges so telling us that their modem is worth £99 is just part of the big con (imho).
Mind you, it's a good job BT are there - it gives others like TT and PlusNet a good starting point for price comparisons where they can state "Save over £110 against BTs 18 month contract). I notice TT doesn't use PlusNet in their comparison table, just the three most expensive ISPs.
(btw, I thought PlusNet were part of BT?)
No, you probably will not notice much difference in practice, although you might even get a better speed from one or the other depending on which ISPs have been LLUd at your local exchange. Google samknows and your local exchange name.