With regard to the availability of functions, the Icoms and standard horizons are all coming into the UK programmed to a specific SOLAS spec, the spec is decided at an international level and the UK distributors (Icom UK is a distributor of Icom Japan) only have the option to remove each unit from it's packaging and reprogram it prior to sale so for example if I buy something directly from Icom, I'll email their tech guy and the kit will be reprogrammed prior to dispatch.
Any Dealer should be able to do the same, the likelihood is that if you buy from a big supplier, they are possibly keeping costs down by not offering this service.
I've always been willing to pay a little more to have a person who I know I can call to sort a problem, before or after the sale, i know the name of the guy at Icom who knows everything about the whole range and talks me through the tech that I don't know, I can't give his number out but I can take any questions directly to him
We love ( I think I mentioned that earlier) the M93 and in supporting it, I wanted to be able to let users access extra features so we bought the dealer software and programming cables, we can enable various extra features on the current Icom range if you're in the poole area and can bring the radio to us.
hope this info helps somewhat
again, feel free to pester me with any queries.