Would it be worth to spend an extra 4500$ ?
The RV-12 runs very close the max speed allowed for LSA in the US. This is accomplished with Rotax 912ULS and the 2-blade ground-adjustable Sensenich prop furnished by Vans.
My 12 easily cruises at 135 mph IAS even at low altitudes. Initial climb with two people onboard and full fuel is nearly 1000 fpm. I have flown cross-country with a Piper Cherokee 180 operating at 65% power and can easily match speed. Likewise, I have flown with plenty of Cessna 172 Skyhawks in the traffic pattern and can pass them in climb every time.
So, to answer your question, at $4500 USD I don?t think you?ll get a return on your investment. I don?t know if Europe allows in-flight adjustable props, but that might be worth considering.