I have both cameras (well, my wife has the E620).
To me, when it's in the bag I want my camera to be the E620 (because of the weight). When it's in my hand I want my camera to be the E30 (because of the ergonomics and the differences mentioned by you and others).
Because I feel having a camera is more about taking pictures than it is about having one in your bag, the E30 is clearly the one I like most
I ended up taking the E30 whenever I expect to take interesting pictures, and taking the E620 when I want a camera with me just in case.
Some thoughts on the differences:
Balance
The balance of the E30 is much better. When using big lenses, you must support the lens and camera with your left hand when using the E620. When using the E30 you can comfortably use both hands for supporting, or even your right hand when needed.
When adding a flash, the E620 balance is even worse. Especially with 4 battery flashes, I don't feel confident with the E620. Afraid I will drop it all.
Focus speed
The focus speed difference is quite big in my opinion. SWD lenses focus much faster with the E30, low light focussing is faster with all lenses, and lenses like the 50mm f/2 (which sometimes are difficult to use when fast focussing is required) benefit big time from the E30 focussing system. When selecting diamond as your focussing pattern that is. I think that the four focussing points surrounding your main focussing point help in deciding the correct focus distance. I get far better AF performance in this mode with most of my lenses.
Portability
The E620 is the clear winner here. As long as it is in your bag ofcourse. But when coupled with your 50-200, the difference in weight is not so noticeable. Only
when using a light lens as well you will fully have benefit from the light body.
Image quality
If factors like focussing speed/ accuracy, IS etc are not making a difference in your output, then the cameras will deliver output that is hard to tell apart.
Bottom line
This is just my opinion, but I'd say that if the weight difference is very important to you, you've held the E620 in your hand and it feels right for you, by all means, go for it! In all other cases, go for the E30!
Good luck in choosing,
--
Regards,
Gravi
Olympus E30 & E620 and a bag full of lenses and stuff