I have a Hillpower chip and thinks its excellent VFM. Noticablly smoother and quicker...
The extra price that bb charge is probably due to the fact that they will set it up on a rolling road mapped uniquely to your car. TBH i think this is only justified if the fueling/timing has been vastly modified on your car (e.g. with cams, new injectors, headwork etc) so id just go for the Hillpower one.
The Hillpower chips are mapped to specific mods, just not uniquely to your car. Oh - they will also provide a re-mapped chip for just 35quid as long as they do the work/supply the parts on any further mods....