Globaliser,
I always try and sit back to let everyone else off. Can usually get in an extra 5-10 minutes' reading etc each time. Try and make sure I don't keep the crew waiting, and bags are often in reclaim by the time I get there. Would only rush a t'fer if absolute "short" connection, and have been given seat further up + inbound flight is delayed.
BTW, IAD ultimately has just the one big "terminal", with various concourses as mentioned.
AFAIK, this would mean that you would not have to go through security again to make the onward connection.
Do you have to go through security on arrival, like at ATL? Have only flown from there, not to or through it - lovely Saarinen terminal - one of the nicest (still in use) in the US! Perhaps second only to DEN!