To be honest with you, if you would have dedicated buttons and a top LCD you would think going back to using ONLY the main LCD is a total mess.
Personally, I think its better when have to press few buttons and in a second you have the desired settings, while YOU have to go through all the menus, if you ask me, it can be a reason for a few missed shots, but that's just me.
Not entirely true. I used to use a 40D while I was in University, and never once did I ever use the top LCD unless it was really sunny. Its only personal prefference.
As for "quick menu settings" Olympus has all 4 of the biggest used settings on buttons. plus shooting modes/timer, flash, a custom function button, an exposure compensation button (that you can set as default without pushing a button, jsut turning the wheel) and for a cheap camera, at least they give you a wheel, as opposed to a camera I used to have that had an up and down button (the brand escapes me, but I think it was nikon or something)
When it comes down to it, a few missed shots in my opinion is not keeping your camera pointed and looking through the viewfinder. Looking at the top LCD in my experience has made me miss shots, becuase I had to move the camera out of the shooting position. With an LCD (and the internal numbers in the viewfinder,) you only have to move your head back and the camera is still pointed.
Also keep in mind, the Olympus system has a dedicated Live view button, the 40 does not have this, you gotta set it up in the menu, but then I had problems of always hitting the SET button when I was using the wheel, because the button was so acessable. In terms of dedicated manual controls, the 510 and 520 have all the major buttons there..... unless you want another dial, or something to adjust sharpness or colour, or saturation, gradation, contrast.... (all of which are accessible via the quick LCD menu (something that a lot of pro cameras dont let you do, OR force you to dig deep into the menu system) with the olympus, its still all there, its just 3 more extra button pushes to get it to work... and for a small camera, I think people ask too much from it.
1) Olympus OM1 [Zuiko Auto-S 50mm f/1.8]
2) Pentax MZ-60 [Sigma 28-90 & 100-300]
3) Canon 7D [EF-S 15-85 & 70-200mm f/4 IS & 50mm f1.4]
4) Leica M [50mm Summicron Pre-aspherical - Silver]http://www.poetproductions.net