Can somebody tell me what's so great about it?
No, i cant. Just my belief:
In my town there are three high-end dealers, none of them deals with rega anymore. One of those three dealers is the one im dealing with since 30 years and he throw rega out due to several problems, especially for the behavior of the german importer in case of faulty units, what was not customer-friendly.
The tables dont sound bad, but the workmanship is poor for the money and problems occur from time to time.
I don't understand the probs you have had with the xpression. As you described it (IGD), this sounded like a cartridge misalignement to me. In general, the xpression is a fine table, the problems you described are not typical.
For the price of an RP3 with some "upgrades" you can easily get an xperience or even perspex-table...
but, as i said thats just my opinion.