The views of an interested outsider here...
Is noise pollution not going to be an issue? The peaceful natural environment is Alderney's main attraction to visitors (like me last summer!). The Dorniers are a little noisy but the noise is not half as pervasive as that of an EC-155. And as has been mentioned, freight costs on a heli must be eye-watering!
They seem to be having difficulties getting access to the UK and France markets with 2-reg aircraft. I'm not an expert on this stuff, but if so why not just get their aircraft G-reged?
By coincidence, Isles of Scilly Travel announced yesterday that they are starting a heli service from Land's End to St Mary's (and thus increasing noise pollution in this year's holiday destination
). I'm struggling to see the benefits of heli over fixed wing...