Jeremy, I have found that with a PVS 14 you sometimes don't realize how tall the grass or crops are. Same with thermal too, in fact it is more difficult to distinguish lower from taller grass or crops with thermal, but when you see backs of critters you get the clue needed to realize that the crops or grass are taller than you thought. In that situation it is unlikely you would spot the critters at all relying on NV of you're on the move. Different if that's the field your stand is overlooking, when you will eventually spot some motion.
On thermal spotters, here are a couple of observations for thought, pretty obvious but sometimes overlooked.
1. If resolution is high native magnification can be lower, if resolution is lower native magnification ought to be higher. Native magnification does make up for lesser resolution to a degree. But see #3 below.
2. If your scope is high resolution you can get by well with a lower resolution spotter, and vice versa. But if one isn't high resolution there will be a lot more situations where making positive ID is delayed, especially as range increases.
3. FOV is really important, and the more the better, but then see #1 above.
Some of my night hunting involves big fields and longer ranges, some involves tighter fields, some mixed cover or in the woods. I'm using a Pulsar XD 19A as I noted above. I really, really miss my Patrol for the purpose, which offered nearly the same field of view and native magnification but higher resolution. I choke on the idea of spending a lot of money on a non weapon sight, dedicated thermal spotter though. I know some native magnification would improve spotting on open ground since my "spare" thermal scope is a Pulsar XD 50S which though a scope with a better screen, bigger lens and 2x native magnification, has the same guts as the 19A, and I can see more critters at greater ranges and make faster more sure ID with the 50S than the 19A. I think the varied terrain I hunt favors a wide FOV though, and I can live with having to swap to my IRD 2.45x native magnification MK II for ID at longer ranges.
If bigger fields were a greater majority of the terrain I hunt I think a Pulsar XD 38 spotter might be a better choice.
JPK