I went with an Omron R7 this is meant to be Clinically validated although I have just mailed them asking for more information regards this claim.
Omron R7 has Intellisense which helps with correct placement, which matters a lot, I did buy Omron R2 which has Intellisense but not Intellisense placement sensor so you can still be off target and I sent that back due to constant wrong readings.
To calibrate with doctors is a simple case of taking your monitor in and doing two test one after the other, it will not matter if you suffer white coat syndrome as both will read high so no problem calibrating.
Opps forgot to link :
http://www.omron-healthcare.com/en/produ...637-E.html