I'm debating the same thing - but for my soon to be 5 year old DS who is 51lbs and about 46 in tall! My DS was 38lbs and 38in tall at 3 years old when he outgrew his 40lb car seat.
I can try to find out what the dates are on the albeebaby seat elsewhere. I think if we buy our seats now, we'll have seats that are at least several months old - but not years old. I bought out other Regent in February from hipmonkey.com and the seat arrived within 10 days of when it was manufactured.
Look at where your DS's shoulders are in relation to the harness strap. The harness strap must be AT or ABOVE his shoulders. If his shoulders are above the strap, then he has already outgrown the seat.
