When I bought my golf, it came fitted with a Sony headunit and CD changer. While it's quite good, I've always preferred the OEM look and I'm now considering buying a standard golf headunit and in dash cd changer or and MFD with cd changer

Has anyone done similar and will I regret it in terms of sound quality??

MK IV or Mk V Golf?

Mk IV...

Also, how much should I offer someone for an MFD (Version D or G)?

I'd say keep the Sony and change the speakers if you want better sound at a later date.

The bogo head units in the MK IV Golf/Octy Mk I etc were all IMHO sh*te.

If you had said MK V I'd have said the MFD2/Audience equivalent or Trinax would have been fine.

You could find something like a becker too as they look more OEM that the light up Sony units.

I might keep the current set up then and save me money for a remap or an ARB or some new springs...