Those Hoovers are great, look like small sc-fi type robots -they're screaming out for 2 big eyes (sorry, it's this damned Henry obsession, I put faces on everything- lol )
I like the carpet cleaner type head - something else to now look out for 
I have the Airobrush & it works very well but I do find that there's not much articulation on the neck joint of the tool so if I raise the pipe it tends to come off the carpet & make a heck of a din ! (might just be poor technique on my part though).
Conversely I find the Numatic Hairo brush excellent in this respect, as the articulation is great, although the head is by design quite small.
Can I just ask, are the aftermarket filters worth getting? The genuine Numatic ones are quite dear, so if the cheaper option is worthwhile getting those would save me a few quid.
Cheers
Dave