I've definitely pushed my van a bit (2016 144" with after market duratracs). The 4wd is definitely disappointing but I knew it wouldn't compete with my previous stock tacoma going into this. Here's what I've found:
I live in western Colorado and so far have taken the van over Cinnamon pass (no problem), 12-15" fresh snow over road surface (did well enough), and through some spring runoff creeks, mud around Crested Butte.
Dropped into one creek that ended up being ~3 feet deep and flowing pretty fast. The channel was maybe 20' wide but had to cross another 50' of 1-2' deep water with mostly rocky bottom. The van performed well enough to cross that but got a little stuck on the far side. the far side was 6" deep, flat, sandy bottom (tail pipe clear, not high centered). This is where the electronic braking/computer crap had me wishing I was in the tacoma. I bogged down a bit, wasn't sunk or stuck necessarily but I could floor it and bascically nothing would happen (minimal increase in RPMs, no power to wheels at all). In the past when this happens (loose terrain) I'd just stay on the gas and let the braking/computer do its thing. In my tacoma this would have landed me stuck on the frame, but that's not how the van works. I then switched into 4 low, tried ASR on/off; no avail. After 5 minutes of screwing around, I put van in neurtral, raised RPMS up and dropped it into drive. This woke something up and wheels started spinning and was easily able to rock myself out. I'm not sure how to explain what happened here.
Later that weekend I went to cross a mud hole in the road; 2 wheels (passenger side) in 6" deep mud and 2 wheels (driver side) on decent ground. I was level and van quickly became stuck. Not high centered. It didn't throttle down this time but no amount of flooring it, gearing down, ASR on/off; all made no difference. The mud wheels just kept spinning, no help from brakes transferring power to traction side here. I tried jacking up the front passenger corner and backing out, no avail. Van came out with easy tug from rear.
Needless to say I'm not real psyched on its performance, but I didn't expect too much and I needed to know where the limitations would be. This experience has had me looking into lockers and/or a winch. The limited power to the front wheels is noticeable and there is basically no flex. It's been an adjustment but still love my van.