Mobileme makes no guarantee of service availability or data integrity. For example, what would happen to your business if you were one of the people who had no MM mail service for 7+ days? What would happen if your idisk files were to suddenly disappear (like those of
this person)?
And what does "Guarantee" really mean? Like 99% uptime or we will give you a free month. Or what?
I have been using GoDaddy for some time and have had very few problems. But they don't "Guarantee" anything.
Read: 11. LIMITATION OF LIABILITY.
https://www.godaddy.com/gdshop/agreements.asp?ci=8924
I think a lot of small businesses use them.
Whatever service you use I think you need to consider having a backup plan.
In my case I have been using GoDaddy for email and web hosting for many years with very little problems. I did have a problem with my web site (it was my mistake) so I contacted them to get a restore of a database file. They were able to do it but it took a while and I had to pay extra. Since then I don't put anything on their site that I also don't have duplicated on my own local servers.
As far as MobileMe Contacts and Calendar I have Sync Copies on my PC and I also do a backup every night. As far as email on MobileMe, so far it is just a copy of my main email. I am still on Trial of MobileMe, but if they can continue to perform (I have had very few problems), I may convert to purchase and use it for others in my office that also have a iPhone. For me it is this or an Exchange Service.
I am just saying that you should provide you own insurance. And if you do and you need the Mobile Solutions provided by MobileMe then it might just be a cost effective solution.
Also, keep in mind that most businesses should have their own domain name for web sites and email. MobilieMe currently does not allow personal domain names.