My PVS-14 thoughts:
Couching your expectations is key. Night vision allows you to see at night, better than your natural night vision. Don't expect anything like what Hollywood sets you up to believe.
The more IR sources you have, the better.
In general, people talk a lot about the cost of the unit but the accessories add up quick too so take advantage of the experiences of those who have gone before you. I almost bought a new Rhino mount before I found out that they are on Ebay and likewise for a steal. Same with a 3x magnifier. Since I am never betting my life on the equipment, used accessories work just fine for me most of the time.
Here's my tip: go with the Gen 2 Rhino mount. The weight savings is worth the slight increase in price (if shopping on ebay/used market). Paired with a Crye Precision Night Cap.....phenomenal
WEIGHT! Maybe i missed it being said, but weight adds up quick as well so keep it in mind, especially since you are typically putting all the weight on your head and not even centered on top....be prepared the first time you go on an hour long night trek because it will take its toll on you
Weapon mounting is fun, but not as useful as head/helmet mount. So dont feel the need to blow the $$$ on a weapon mount. If you never get one, you aren't missing out on much. An IR laser is cheaper and more versatile.
Ive had my PVS-14 about 6 months, only used it for prolonged periods of time roughly 5 times, but its already proven it was worth the money. Just going out on a pitch black night and seeing all the stars that I couldnt see with the naked eye was awesome. Sneaking up on a deer in the woods was amazing.