Hi looked at them but not too keen on the drill driven idea as prefer direct motor driven one and as this has automatic speed control as well seems a good deal. ...
Umm. "Automatic" ?
I thought it had 10 speed settings - click-stopped so to speak.
I must say that I rather like the not-click-stopped (fully adjustable) speed control on mine.
An extractor is a big lump to store (hygienically) from one extraction season to the next. And a 20-frame jobby is going to be a BIG lump. Better check (ahead of time) that it will fit through any doorways that you might want it to!
Also, the bigger the extractor, the more honey gets left behind, stuck to the extractor! This isn't too much of a problem for the 100-hive man, but its going to impact your yield if you are just trying to extract a couple of supers....
Motors and controllers do occasionally fail.
The thing with the drill-powered option is that you can fix it yourself, quickly and cheaply by just buying (or borrowing) another drill. When you want your extractor, you do not want to be waiting while bits are sent away. And I would also suggest that it looks as though the vendor might be the only source for spares and repairs to the controller (I'd expect the motor to be pretty generic).
Second-hand extractors sell for a very high proportion of their new price.
You would lose surprisingly little if you bought a serious-hobby (9-frame radial) model and decided after a few years that you needed a bee-farmers' version (20 frames or so).