Yep. I had an 'A' RNS510 and it was slow as hell to boot up, very slow to load media from the HDD and the NAV was borderline unusable. I put a 'Q' in recently and that is loads faster and better in all respects.
Mine's an 07 ED30 using original canbus. The later 510s can have the battery drain issues solved internally with a software adjustment. Earlier 510s need a newer Canbus to solve the battery drain.....and if you want to change the CANbus, you have to take the wipers off, the scuttle cover, remove the wiper mech and the access panel and then you can get at the CANbus box. To do it from underneath inside the car is a total nightmare if you have man size hands.