I've just fitted some D207RR's to the ST4s and to be honest with you I preferred the Avon Azaro ST's that were on before. But as I dropped on the tyres for £75 the pair I will persevere. A pair of Avons will set you back £145 at BFM @ Saltaire and will give you the best of both worlds with the compounds used.
http://www.bfmmotorcycles.co.uk