TweetRing for my girlfriend... I dont think I would sell my bike for that!!
The 600 is a great bike for a new rider.
Like any older 600s, after you get used to them you will want more..
I would think the speed would be comparable to the Magna you mentioned
Also the 600 is noticeably smaller than the 900 or 1000..
They are very popular and I sure the resale would be there for you.
Overall the 600 is a very good bike.