I got my 601 today.  Some observances:
The button top batteries will charge in the standard 601 charger.  The button top is partially exposed, but it makes enough contact to work.
I will also happily confirm that the button top batteries work fine in the pipe.
I've been sucking on this thing since I got it about 2 hours ago.  I love the feel of it in my hand... something I've missed since I stopped smoking a pipe a while back.  I'm not terribly happy with performance.  I can get a decent hit if I suck for about 6 seconds... but not the occasional light puff that I enjoyed with a real pipe.  I imagine that's because it's only 3.7v, and the atomizer is so far from the mouthpiece.  I'm also not getting the large volume of vapor.  It could be that I got a less than stellar atomizer, or that it needs to be broken in.
I've found what I consider the perfect flavor (for me).  I combined Liquid Xpress's Cherry Cordial with a little Lorann's Chocolate.  My favorite pipe tobacco was Cherry Cavendish, and this comes close.
I'd also like to pass on a great deal that I've found... Midwest Vapor is going out of business, and they are selling the mouthpieces for $2.50 each.  I just bought 4, for a total of $15.50 shipped.
I'm sure I'll add more follow up.
Oh... thought I'd add that I haven't picked up my Prodigy since this got here!  (Of course, it's only been 2 hours).