Gas-Can's a good guy to talk to on this!
My perspective: Think of them as two different scenarios...
1. overcast, no-moon nights
Gen 2 will still work here. Part of your decision to use or not use IR illumination depends on your gear and your use. I'd always suggest buying an NVD with manual gain. If you're out checking the cows, or scouting for yotes, an IR illuminator/spotlight with your manual gain turned down will help a lot. You add some light to the scene, get some reflection off animal eyes etc, but not wash out the scene. If you're in a position where your worried about flagging yourself with IR light, Airsoft/Afghanistan/Whatever then you crank the gain up and get a more useable scene.
2. Indoors, no-ambient light conditions
Gen 2 will still work, but the hardest part will not be brightness, the hardest part will be reaching for an opening a door handle etc. Your focus is unlikely to work as well indoors using Gen 2. When there's no light you want an IR flood light. So something low power with a wide beam rather than a focussed illuminator. Most good NVDs will have a built in IR source, but the surefire helmet lights are also a good (relatively) cheap way to get diffused IR light.
Gen 2 versus Gen 3 is a hard choice to make. You can get decent Gen 2 for under $2k, but it seems that you can't get any legit Canadian Gen 3 for much less than $5k. In the USA they get Gen 3 for $3k, so there I'd choose it everytime. But up here, you really have to evaluate the cost-to-improvement ratio.