I've never played an older D120 but would like to. I owned a Series II D120 and Series II D60 and didn't like the new D120 much at all. It was just too open and I love an open gain structure. It also lacked saturation and was very dark until you cranked the treble presence which I don't mind doing, but doing so just made it sound really harsh. The Series II D60 I liked more than the D120, but it still wasn't a keeper.
The Older VHT era D60 I owned years ago killed as does the '07 I have now. Top 5 for me easy.