I'll be honest and I have a MAXX Pro Grinder with all the whizz bang grind into the cutter on both sides stuff etc etc. I like it and do get really good results. However, I do plan on buying another grinder to use as well (as a back up and to have one set up for sharpening and one for depth guages), and I'll be buying the hydraulic vice Oregon workshop version (not sure of Model number) even though in Australia its about $100 dearer.
The only problem I can see of the MAXX compared to the Oregon version I just mentioned is that;
1) On the Oregon models the wheels are easier and faster to remove and put back on the machine when swapping sizes or changing to the depth guage wheel (not a big deal but is a pain when you're in a hurry and have a heap of chains to grind). I've been doing a lot more grinding than normal as I got hold of 3/8" .063" Carlton Ripping chain for USD$110 for 100' so am grinding it to 30° and doing the depth guages to suit - ah lah semi chisel, just about 15% shorter cutters than new semi chisel
2) Despite favouring the "grind into each cutter" left and right advertisements, I have found that although you do get a few more burrs when grinding away from the cutter, in the field its not noticable - I've just found that grinding away from the cutter can create more heat on the cutting edge than grinding into a cutter, especially if you have to take more metal off. I was a big believer in grinding into the cutter a while back but in reality its not that big of a deal.
3) I have noticed some flex in the plastic/nylon chain stop adjustment arm that I didn't notice when using the pro Oregon grinders.
4) The biggest concern - Every time I swap from grinding left to right I have to readjust the depth setting and the cutter length. If the machine was completely square (can't think of the right word at the moment!) this shouldn't happen as far as I'm concerned. I also remember this being part of their marketing ploy.
However, if you sharpen a lot of chains, the auto vice clamp is awesome
I have also heard of a problem with the odd hydraulic vice clamp leaking on the Oregon model but I'll take my chances.
I believe the MAXX is better than the 511A and AX etc now that they've banned the reversing switch but not better than the hydraulic Oregon. If you know someone that can install a DPDT switch for reversing then even better although that'll kill your warranty. I plan on doing it to my MAXX soon to speed things up even further
Sorry about the long post but hope it helps.
Matt