I know this thread is a few months old but since a few mentioned about upgrading to the RNS510 style unit from ebay, I would think twice. Below are my findings so far the unit cost £310 so I thought it would actually be a reasonable unit, it really does look the part and is very easy to use however these issues are found in less than a week.
The DAB stopped working within 5 mins (they are replacing the black box to see if this fixes it)
It takes about 2 minuets to boot up, useless if you want to have a reversing camera!
The FM tuner is rubbish!
The sound quality is rubbish (half the quality of the standard unit)
CDs dont play like in any normal head unit, the volume difference between radio and cd is massive. On CD if you turn it up to 15 it gets louder but above 15 and to max at 30 it gets quieter.
The Bluetooth microphone is terrible and not usable.
I think thats about it for now but overall not impressed! The seller claims he sells about 200 a month and has never had any issues before so yes I may have a dodgy unit which he will have to replace, however I will just want a full refund. Had this of been one of the £100 ones it would be expected. I will be contacting Preston ICE, if there unit has none of the above problems it will be worth the £450 or I will stretch to something like a pioneer one at about £600