Holla, that's a tough question. I just got my G2L today, and I have a 9p with P91 and a G2z with P61 to compare it to.
I have put a brief review in the G2 LED thread on the G2L.
As far as the G2L and G3 question go: If you have a choice of one or the other this is what I would do:
Buy a G2L. Take out the P60L, and sell the rest. If your existing G2 does not have a LOTC, keep its P60 and sell the rest of that one. Put that money towards the G3 and a P91 bulb.
Why do I suggest this? If you love your P60 in the g2, you will discover a new love with the P60L imho. You will never need to buy another lamp assembly again as LED's don't burn out / fail etc. If it does, its under warranty.
The P60L off initial specs is compatible in the G3 with 3 batteries (longer runtime, not brighter as I understand). This way if you want to use the G3 with the led, you can throw your old p60 in the g2 and you will still have two usable lights
Why get a P91? IMHO there is not sufficient improvement in the P90 to offset the runtime / 3rd battery etc against the G2L. Yes it is brighter, and the hotspot is substantially wider. However if you really want a 'wow,' 200 lumens is a better visible difference. IMHO 200 lumens is the minimum amount of light for 'tactical' (can't think of a better word at the moment for it) type purposes. Sure 65 lumens is Surefire's minimum for dark adjusted eyes, but in my opinion 200 lumens is substantially better (particularly when ambient light is around). More than that and you start to get 'bounceback' from walls indoors etc, so for me at least the p91 in the 9p and HOLA in the m3 is perfect.
I get the impression cost is the main issue over getting one or the other. If its not I'd just say get both and use the old g2 as an emergency light in the house or car etc

. If cost is an issue, you won't want to be spending big on batteries. In that case, the G2L would be my recommendation. Plenty bright enough, and GREAT runtime compared to the G3. 20 minutes runtime for the P91 is acceptable for me because I only use my surefires in 'flashes,' not constant on. one set of batteries can last me 6 or 12 months because I have a L1, or aa lights for general use.
If you could tell us its intended use we might be able to make more specific answers.
Hope I helped
