Called in at VW today to pick up a courtesy car as they're replacing a caliper on the GTI.
Nothing to note on the diagnostics front I'm afraid Vanstring. Mine does drive really well, and very very rarely exhibits this 'holding' characteristic..
I fully intend to replace the usual bits anyway (dv, pcv etc), as I know there can often be a hardware issue that the ECU can't/doesn't pick up.
Best of luck with yours anyway, fingers crossed you get it sorted.
If it makes you feel any better I'm driving around in an Up! for a few days....! Hehe