I've had two Wally chippers - BX42S and now BX62S.   Both were/are fantastic.  The 6" capacity of the 62S works my fat azz to the bone.  I maintain my pine forrest out here.  That means thinning & chipping the stands of young pines.  Every spring - identify, fell, drag & chip upwards of 900 small( 6" or less, on the butt ) pines.  This will usually take me a month.  Green pines chip easily.  Dragging a 6" x 30' pine - not so easy or fun.   Slowly but surely I'm turning my 80 into fields of pine chips.
What will you be running it on - 
M7040?  If so - you will never be able to keep up with the speed of that 60s.  It will work you til you drop.
I upgraded to the BX60s when I bought my new Kubota 
M6040 in 2009.  After nine years and chipping all those young pines - I still haven't had to sharpen or reverse the cutting blades.   Maintenance - grease the two zerks every ten hours or so - clean out the cutting chamber when you are done chipping - coat the four 
chipper blades with some heavy grease when it's put up for the season.
My best suggestion - keep it clean.   Try hard not to drag whatever you're going to chip thru the dirt and mud.  It doesn't do your hunting knife any good to try to cut a rock - it won't do your 
chipper blades any good to cut dirt & mud.