Redeem mortgage and pay 2%? or not?

I have a £100,000 outstanding mortgage with C&G on a house which I bought in 2012 for £157,500. The mortgage is split into 2 sub-accounts (SAC)

SAC1 £30,000 0.67% (BoE+0.17%) - 9 years left
SAC2 £70,000 5.89% fixed until Feb 2015 - 22years left

SAC1 is on interest-only as its virtually interest-free from a previous mortgage I ported in. SAC2 is the extra I borrowed to top-up when I purchased this house. I overpay £50pm on SAC2 and my total monthly payment overall is ~£550

After getting my annual statement I have decided it might be worth spending 2% to redeem the (now expensive looking) SAC2 and move it on to a new 5-year fix cheaper rate. C&G are offering 3.94% (no product fee) on a up to 60% LTV so if my figures are correct, the 2% redemption fee will mean I "break even" in the first 2 years compared to interest paid leaving the subsequent 3 years to save me oodles of interest. I will also reduce the term to match my ~£550 pm payment.

(Ignoring SAC1 completely..)

IF I DO NOTHING.... After 2 years on SAC2 @ 5.89%+£50pm overpayment my debt left will be £65,420 (£524pm)

CHANGE DEAL & REDUCE TERM TO 17 YEARS..After 2 years on SAC2 @ 3.94%+£50pm overpayment my debt left will be £62,829 (£521pm)
factoring in 2% redemption = 70000*.02=£1400

I'm better off by paying £1,191 less interest just in the first two years.

Can anyone see any holes in the plan and any more advice? I'm going to see the mortgage advisor tomorrow lunchtime.

Thanks