Lee its based on £77,000 Turnover not earnings, but I am sure you knew that !
Its not worth the hassle of registering if you are only just going to go over the threshold you really need to jump from the £77,000 to at least £100,000+ mark to really make it worth while, (eg taking on another company)
20% increase is a big hit for a customer , I think a lot would not be very happy in the present economic times
Also trying the De-register for VAT ( if your turnover drops back below the threshold ) and HMRC are ALL OVER YOU really not worth the hassle for a one man operation
I personally think George missed a trick at the last budget he should have raised the threshold by £10 / £15 thousand to help small business who want to grow.