Always the contrarian I'll disagree with the conventional wisdom and say that no, you MIGHT not need to spend the extra on hyd feed.
Mostly depends on how you'll be using your Maxx.
In my case, pretty much anything above 4" or so is firewood so the feed speed issue others speak of isn't a problem 99% of the time and when it is I modulate by lifting the infeed roller.
If money is no object then by all means go for it, I'm sure you won't regret the purchase and as they say "it only hurts for a little while".
OTOH though, if your usage will be similar to mine I think you'd be perfectly happy with the mechanical infeed - I know I am.
Two years and probably a couple hundred hours on mine and I can count on one hand the number of "jams" and only one time did the
chipper ever stall the tractor (28hp Bobcat) and that was when a chunk of 3/8 cable snuck in and wound itself around the flywheel shaft.
All in all, I continue to be amazed at how well built, designed, and functional the Maxx is - even without hyd feed.