O2 200 online for 18 months (400 mins offer) - anything better?

I'm looking at O2 because Orange simply cannot offer me a more attractive
tariff at the moment (I'm 6.5 months into contract).

Getting an 18 month O2 200 Online contract would give me 400 xnet mins, 150
texts and 1meg of GPRS.

At the moment, I'm on Orange Yourplan 120, paying £2 for texts and £4 for
GPRS. I'm using almost 400 mins a month though.

I'm temtped to go for the above offer on O2, then change my Orange tariff to
something like T-Mobile's Freetime 750 for £16/month.

I'd then have the benefit of the 400 mins I usually use, plus 750 off peak
mins, for a total of £46/month, rather than the £57 I've just spent on
Orange...

Si.