I see your point Westcoast, and I must thank you for the compliment. A photographer works with what he or she has, and the D-Lux 5 has proven perfectly capable of helping me shoot real keepers. So how doesn't that stop me from spending well over 8000 euros on the M9 + lens? Let me see.
One thing I've been missing with the D-Lux 5, is the ability to control depth of field the way I used to with a DSLR. Being a compact, albeit with a decently large sensor, it doesn't really allow for out-of-focus backgrounds. Surely, my DSLR and prime collection could satisfy that need, but that system is too big, too heavy, to intrusive for street photography. Plus I don't feel the connection with the camera if I use a DSLR. The narrow through-the-lens viewfinder (in contrast to the wide, open rangefinder concept) just doesn't work for my style of shooting.
That's why I've been using the D-Lux 5. It's lightweight, small, unobtrusive, very quiet, all great for street photography. But it has its downsides. DoF, as I mentioned, but also the speed of it. I've missed some decisive moments because of the shutter lag or the start-up time. And composing shots on an LCD-screen is far from ideal. Also, while prints look good at 20x30cm, I don't think the D-Lux could go a lot larger than that, and I'd like to. In the M9 I'm looking to overcome those shortcomings. Higher resolution combined with the truly amazing quality of Leica's lenses for the prints. Compact and light enough. Composing through a proper viewfinder. The ability to shoot almost instantly once I master manual focusing. And the connection to the camera. There's no extra, unnecessary controls, no gimmicks. Just a camera. Shutter speed dial, aperture ring, focus ring, and an ISO-button at times.
That's my ultimate goal, to get more familiarized with the basics of photography through using a Leica. Having such an expensive piece of gear motivates me not only to go out and shoot more, but also to try new things. The D-Lux 5 is making me lazy: manual exposure is too bothersome on it and the zoom is just too hard not to touch. I don't want to use zoom, but if it's there, sure I'll use it. It's about the experience of shooting. Eric Kim said, and I'm paraphrasing here, that some people buy a 30k car because it's a better drive than a 3000$ used truck. Both drive, the other just makes the experience of driving better. I feel the M9 will do the same for me. It'll make me feel more like a street photographer, more involved, more connected. More inclined to switch to exposing manually and dance around the streets like Cartier-Bresson. It will allow me to walk the streets, quickly lift the camera up to my eye, snap, and continue. Now I haven't had enough time to shoot with the M9 on my two visits to the Leica boutique in London, but I know that the M9 can be an extension of my eye, as it is for many photographers. A compact simply can't. It's a good instrument for shooting photos, but not the best. The M9 is, and it's thus worth the 1.5 years of saving, to me.
I feel one just knows when a Leica would be the right camera. If you don't, it seems nothing more than an overpriced, old-fashioned camera with lots of missing features. To those who buy it after a long time of saving (i.e. not rich people looking for an accessory), it's something different.
Also, to comment on your Costa Rica birding trip. I love being in nature, but I don't like taking photos of it. I've been planning a trip to NYC, and with the M9 round my shoulder, I know I'll have the time of my life. It's any street photographers dream (both the camera and NYC

).
If you have some time, and you haven't seen it yet, be sure to watch Kai's video on why the M is so unique:
http://youtu.be/Ykuy4qYip1U
- Bjorn -