There is a Harmon project going through approval in the UK (are you UK based - DA?), but I don't have any personal knowledge.
It depends what you're after. My 150HP RV-4 is not under-powered. Cruise at 130KIAS at 55% power setting, from which you can loop it without touching the throttle, climbs at 1400 ft/min gross or 2000 ft/min solo.
A lighter aeroplane will usually handle and fly better than a heavier one.
Pay your money and take your choice.