For what it's worth guys, there are regularily scheduled European carriers which utilize letter suffixes on the end of their callsigns on a daily basis. I work probably 30-40 of these every day just off the top of my head... and it's the same letter... Eg BAW45B so it's not about the Captain... it's just the callsign... A lot of Euro carriers are starting to use it it seems... I had assumed it was to start cutting down on confusion of callsigns in conjested airspace, especially in Europe with the plethora of accents/operators.
I mean, every day theres DAL118/UAL118/AAL118 all in the airspace at the same time (I don't remember if it's 118, but have seen all three airlines together) Maybe it's not the worst idea to start registering callsign numbers against routings somehow to eliminate this. Generally for the native english speaker it's not a problem, but throw in two separate frequencies/one controller and it gets mucked up everytime.