I THINK the important part of ESOF (or any 4wd) is that you
needed to "turn it on" BEFORE you need it.
the drawbacks of Manual are that pulling the lever is only 1/3 of the
necessary steps...you MUST get out and lock the manual hubs in....
if its muddy or snow/slush etc...then your out and walking in the muck
just to get the hubs locked in.
w/ ESOF you need to move the truck a couple of feet to insure/complete
the engagement.
the failures that ive read about (never personally experianced) on the
ESOF systems is the failure of the hub engagement...which are more
often than not tied to a vaccum leak.
if the hubs fail to lock then w/ the ESOF system you can STILL get out
and lock them in manually...no worse than you'd have to do w/ the a
fully manual system...course the issue is that youhave to KNOW the
vaccum system has failed to lock both the hubs (and the only way
to know this is when the wheels fail to turn
w/ the ESOF system the transfer case is ALSO electronically selected....
electronics fail...more so than mechanical levers...but ive not read about
any ESOF transfer case failures...