:agree2:
A stock 6401 will outrun a stock 361 pretty handily especially in the bigger wood.
I don't know that you need a 7900 top end but you DO need a nice light 50cc saw to compliment the 6401.
The 390 is a fine saw for a firewood cutter and will give you a good service life with good care, but neither it nor the 361 is that much lighter than the 6401.
MY SUGGESTION is that you keep what you've got and pick up something in the 40-50cc range to take care of your "light work".
Financially speaking, trading the 6401 for a 361 straight up, provided they are in the same condition is a "no brainer". Make the trade, sell the 361, buy the 390 and have a few $$ to put toward a MS-211 or a PS-420.
Mike
I have my MM 025 which I really like in the small stuff. What about just waiting a little bit and doing the BB kit to the 6401 and then getting a 50-60cc saw to satisfy that urge? I have lots of saws bigger then 70cc but non that are a new, reliable and safe saw for everyday use. doing a BB kit would solve that issue and help feed the CAD issue to