How does the whole dev off thing work anyway?
Does your device get listed as some sort of blacklist the moment you enter the code on teh website, or do they purely go by your device saying UNLOCKED or RELOCKED when they look at your device? Surely if you get the code but never use it your warranty would be intact.
If it is not the case, wapparently yo ucan make that message say whatever you like if you S-Off so why would you need to worry about temp root? May as well root it proper!
However, about a month ago I changed my contract to the cheapest one going in a Vodafone store, so I am on £15 a month, I asked they do this while making sure it wasn't extending my contract as I said I was waiting for a worthy phone to upgrade to.
So yes, I am also on a 24 month contract but at only $15 a month with a free upgrade to a HD2 winging its way to me.
Working that out £15 x 25 months is £360 over the two years, bit of a steal I think.