Really? I was under the impression that sand/grit is pretty terrible for derailleurs in general? Based on my own limited experience I would have thought that was the case at least anyway. I've been a mostly casual cyclist during my adult life though so I'll defer to folks who know what they're talking about.
What would your own recommendation be then d8veh? I've seen in other threads that you're quite complementary of the Oxygen S-Cross?
All I can say is that from my commuting experience of about 10,000 miles, I never had to adjust a derailleur on any bike, except once, when the gear cable snapped, but that could happen with any type of gears.
For a short while, based on recommendations on this forum, I used white lightning chain lubricant that all ended up in a congealed mess and full of grit around my derailleur, so I had to clean it all off. After that, I went back to my original one squirt of gear oil on the chain every 1000 miles (approx) or when the chain starts making grinding noises, and never had to do anything since. I've used all sorts of derailleur gears from the cheapest to top of the range. That includes a 1000 mile test in one month on salty and snowy/slushy January roads using the cheapest bike I could find (£5) with the crappiest derailleur gears you can get, with zero maintenance during those 1000 miles - not even a clean.
I like the Oxygen MTB because it goes very fast and handles and brakes perfectly. The City version is not so good as the MTB in handling and braking, but is still fast and efficient.
I have a personal preference for basic Chinese electrical systems because they're dead easy to fix if anything goes wrong. Even if you can't get original components, you can mix and match, and they're easy to upgrade too. I feel really sorry for guys that spend a lot of money on something like a Trek with Bionx motor. It's only a mater of time before you get an error code on the display, then there's nothing you can do except take it to a Bionx specialist, if you can find one. Then, you have to pay whatever he says, which might be £800 for a new battery.
There are many good commuter bikes from Woosh, Kudos, Wisper, Juicy and many others. They all work and you get good support from all of them if ever you needed it. I would buy and be happy with any of them. I think I'm right in saying that they can all be derestricted if you know how, and if that's important for you. I'm not recommending it. I'm just saying what's possible because many guys with long commutes do like to speed it up a bit. AFAIK, none are as fast as the Oxygens.