I have not used either but the Testo 760-3 looks real interesting. The only thing from a hobbyist standpoint that I don't like is the 2.5V cap on the diode testing (prefer at least 3.2 to get some white LEDs tested) although the RS Pro is only 2.0V. The capacitive ranges are much better on the Testo (down to 1pf vs 1nf and up to 60mf vs 10mF) as well as the voltage settings going down to .1 mV on DC as well as AC. The RS Pro has AC+DC current support and the Testo does not. Testo goes up to 60MHz on frequency compared to 100kHz on RS Pro.
I guess it would come down to if you need AC+DC measurements or better component (resistor/capacitor/DC/Frequency/voltage) ranges as to which would work best for you.