BleuDragon wrote:
You are forgetting that the 580EX II just got replaced by the 600EX-RT.
And I'm happy I got the 580EX II after having seen the price for the 600EX-RT! At least at the moment.
I know about the "buyer's regret" feeling but I think my long-term plan is quite OK.
I started my "DSLR life" with a Canon EOS 500D + 18-55mm and then I bought some cheap used additional lenses. Sometimes I think "Oh - should have saved that money for something really good" but it wasn't that expensive and it gave me some time to learn. Then I started to look into the future. Now I still "only" have the 500D but added some nice glass like the Canon EF 100mm 2.8L Macro IS USM, the Canon EF 100-400mm L IS USM and the Sigma 12-24mm EX DG HSM. I always chose full frame compatible lenses to avoid regretting those lenses when going full frame.
Then, not such a long time ago, I was thinking about a new flash gun as well as I only had a cheap Nissin Di466 - now I had to choose one as well - and after some fighting in my head I got the 580EX II and I'm happy I did so. I'm sure the 430EX II would have been great as well but buying it would have cost the money I needed to get something even better and I knew that I'd regret it, but that's just a feeling as my head tells me that the 430EX II would have been enough for me.
I still keep the Nissin as more than just one flash can be handy.
I always thought about upgrading the body but my thoughts were like those:
- The EOS 600D is slightly better, payable - but the main improvements are the screen and the video mode.
- The EOS 7D is a better camera, but the image quality isn't
really a step up from the 500D. So I'd pay that amount of money for "ergonomics only" (+ speed + weather sealing)
- The 5D II is very good and the image quality IS better it is a bit old and a replacement was to be expected in a reasonable amount of time to wait for it.
Plan for the future:
Lenses: EF 24-105mm f4L IS USM - I'm missing the range and I don't want a compromise like the 28-135mm, although it's not that bad either.
Cameras: My plan is the 5D III. What a great camera! But I'll wait a bit longer until the price falls a bit. I still hope I won't regret having lost all my money when I got to buy that thing.

Flash guns: I'm happy with my 580EX II but I might get a used 430EX (II) or even a 420EX as a slave in the future.
The 430EX II is a great flash gun and you can really be happy with it - and in the future you might be able to upgrade - for example if the price for the 600EX-RT is getting to the level where the 580EX II can be found nowadays. And then you can still use on your 430.