I have owned both the Ikelite housing for the D100 and the D200.
The housing is very good.
I have only had a problem with leakage using the 8" dome port and the 10.5mm lens.
The stalk i had, had a small piece of plastic from manufacturing between the o-ring groove and the o-ring. Once i realized that and fixed it, i have never had a problem since.
I think it is a very robust housing. the port is very secure except for the 8" dome port with the 10.5. This is a bayonet style with a quarter turn. It wasn't completely secure in my opinion but still useable. The other ports where very secure as long as you "clicked" the locks. If you failed to do this, then well, it is operator error.
I'm not sure what you are referring to re: the base.
I really liked the clear plastic. On at least one occasion, i was able to see the dust particle or hair on my o-ring after I assembled but before taking it underwater. Certainly saved me there.
Plus, the TTL on the D200 is spot on when used with Ike strobes.