I've been through a LONG research period on just this subject. I run a sailing school and most of the iPad POS market seems tailored around the food service industry. Having looked at virtually everyone, we are going with SalesVu. They have some GREAT integrated ad-ons for small business. Social/Email Marketing; Quickbooks online sync; CRM; Gift Cards. They also have a solid relationship with Mercury Merchant processing and it looks like that will save us quite a bit of money in discount fees over the year.
Had a couple of bumps in getting set up as is always the case with something that is so imbedded into your business but I seem to be on track now.
One thing, I have 20,000 customers in my client list and it uploaded (with help from SaleVu staff) great into the system. Nice to have access and CRM right on the iPad.
They have a relationship with http://mposgear.comand I plan on buying the Windfall system. Seems well done and simple. http://mposgear.com/detail.php?product=363&category_id=9
Buying the Star thermal printer, assuming the software will allow me to print a customer copy. http://mposgear.com/detail.php?product=2&category_id=2
I'll report back on how this all goes.