I know the original clusters '98-'00 used the "suck & blow" method of programming. Connecting up WDS to the cluster, to download the old cluster info, then plug new cluster in and upload files = job done (it didn't change mileage though). I know, if the cluster was just replaced without using WDS various warning lamps would illuminate (ABS, TCS, glowplugs on petrol).
As you're doing it properly Tony, I think that's why your having no issues, but I didn't think they are plug & play...