Hey, if money's no object, then the L2 is a really cool light - I love mine. /ubbthreads/images/graemlins/wink.gif Whether it's brighter or not than your L4 will depend a lot on the individual LEDs. LED technology is improving, and by this time next year I think it's fairly safe to assume you'll be able to get a much brighter, longer lasting LED for the same money. That's why I said what I did. Nothing against the L2, but the big difference in performance between these lights is the low level offered by the L2, not so much the difference in the high level output. (The low level on L2 is extremely useful!) So if more output is the main thing driving you to another light, I'm not sure the difference in performance between L2 and L4 vs. the cost of the L2 would be worth it to me. But hey, you're not me, so maybe it's worth it to you!
The McGizmo 2 stage switch is available from several folks here on CPF. The "McGizmo" forum tells all about them. You can buy them ready to screw on to the back of your L4 from "The Sandwich Shoppe". (He's got a forum here, too.) I believe Chop, and a couple of other very talented guys here on CPF assemble and sell these. (Other folks here know about 1000x more about custom and modded lights than I know - sorry!)
Hey, another light you might consider is an Aleph series light. Also a McGizmo creation. These are Luxeion III lights with exceedingly well made reflectors that can really throw. I've been considering buying one of these - they appear to be beautifully designed and crafted lights.
Oh, something else to consider - how about a SureFire U2? It's larger than the L2, but it offers 6 different output levels, which is pretty cool. It has more throw than the L2, as well.
OK, I'll shut up - I think I'm probably not helping... Best of luck whatever you choose!