Having had both NTL and Sky, I'd go with NTL. I barely use the red button and this was NTL's only real achilles heel for me, so it's not an issue.
Going with NTL addresses your original problem, which is the status of the STB. With Sky, they give it to you but you own it, so if it breaks, you buy a new one. I notice they've said they'll send a tech out, well they may pay for his time, but I reckon he will still charge you for a new box if he needs to fit one. With NTL, the cabling and the STB always remains their property, so repairs are always free (unless you knacker them yourself somehow). That reminds me, the dish and cabling is yours with Sky also, so any problems with that, you pay.
Sky phoned us yesterday to remind us the 12-month warranty is almost up on the box and to try to sell us an extended warranty.
Naturally, NTL never did any such thing to me in the three or four years I was their DTV customer.