I just upgraded from a c5050 with an Inon d-180 to a d200 with Ike case and strobe. I also purchased the AF105VR, 12-24DX and 18-70DX lenses and the 8" dome and flat port. My impressions:
1-You will never go back. The d@mn d200 iTTL broke after 1.5 dives. However I dove my 5050 once after that and then left it behind. After 1 dives experience with the d200/ike I knew that any 5050 shots would be imadaquate. I can't see the 5050 screen near as well as the d200 viewfinder, I loved the instant AF and a picture every second or less.
2-My wife did go back because she really likes composing with the screen BUT ONe experience with the d200 will wind up costing me a new E-330 for my wife (because it is a dSLR with screen preview) because she loved the instant AF and a shot every second or less.
But:
The d@mn thing broke. Grrrrrr. Was this my fault? I don't know yet. What I do know is that the d200-Ike combo is a bigger, more complicated package which can lead to more user errors and system malfunctions.
It is expensive. It was $7 grand total because I purchased quality glass. (All experts advised this)
On the Other Hand:
Experts here were very good a recommending lenses, settings and procedures. The learning curve was much shorter than another dSLR will be. I did get some very good shots on my first dive.
I was taking AF, iTTL shots from a foot away, then blowing them up so I could really see the fish. I now know what a juvinile trunk fish looks like.That was the power of the AF105VR. The autofocus auto exposure worked very well with the suggested settings (f20, 1/125) With the c5050 I needed 2 INON macro wet lenses to get decent closeups (f8, 1/100) and the fish never cooperated. That is real fun. The Olympus E-330 has no such corresponding lens.
Tom