Thanks for all the info guys :)
I spoke to the seller again and this is what he told me:
It's a 1997 model
The stock PRS machine heads have been replaced with locking Grovers.
The 5 way knob pickup selector has been replaced with a 3 way toggle and push/pull controls for coil tap/split.
He's got it listed as Vintage Yellow, but he said he'd describe it more as 'Gibson Amber'. As apparently 'PRS Amber' is more Orange in colour.
He also said that it's more of a players guitar than a collectors instrument, and said he'd give it between 7.5 or 8 out of 10 for condition.
Due to him being unavailable tonight, and my being unavailable tomorrow night, I can't actually get to see or try the guitar until Saturday morning. So I'll (hopefully) take along my Little Rock and give it a blast to see what I think :D