Wolverine and I have used the Scala G4 successfully on many rides. Sound quality is excellent and adequately loud, provided you get the microphone and speakers positioned correctly - and that really is critical, otherwise speech can be drowned by wind noise or too quiet even at maximum volume. When set up correctly though it is very good indeed - I have spoken to people on the phone who had no idea I was riding at the time.
Range might possibly be as good as the claimed mile under ideal circumstances (i.e. in open country), but in a built-up area, it quickly degrades once you lose line of sight... good enough for going round a corner or two, but not much hope beyond that. The Scalas can link through bluetooth-capable phones as well though, so I guess you could fall back to that if you get beyond direct bluetooth range.
A nice feature we've used is that each unit can link to two other Scalas (which needn't be G4s), so you can have two riders and two passengers all able to speak to each other at once.
One negative point: after more than a year of daily use, one of the speakers became unreliable and I had to replace the base unit; the other set is now also suffering the same problem. so I guess it's a common fault. Fortunately you can buy the base unit separately and there is a choice of replacements: I switched from the original boom mic version (which needed re-adjusting every time I put on the helmet) to a wired type which is always stuck on the chin bar of my Shoei in the perfect position.
I think the only way you're going to get better radio range is with PMR. I've never fancied that because of the need to have a wire going from the radio to the helmet, but there are now some models with a bluetooth link (e.g. http://www.nevadaradio.co.uk/two-way...g8---bluetooth), so using one of those and a cheaper bluetooth helmet headset might be attractive (if you don't mind the deficiencies of PMR: sharing a limited set of channels with everyone else and having to take it in turns to speak).
