at the risk of sounding controversial i have just completed (this week)LHR-BWI and back on BA from T4 with a 5 monther and a three year old and can only say that the experience was pretty painless.
the only real delay being the not so "speedy" bag drop at T4 after checking in online.
Both sectors on time (Early coming back! despite a long taxi from 27R) sky bridge to both aircraft whose AVOD worked perfectly keeping my 3 year old quiet for the majority of the flight....
The aircraft (763's) were clean and crew were fine.....even all of our 4 bags turned up.
i know i'm only a mere passenger but it really was quite good and BWI is a pure pleasure compared to IAD which is complete and utter chaos.
just a two penneth.