digital system configuration

I'm looking at making the Olympus 5050z my entrance into the realm of digital. Any advice regarding the following systems that I'm thinking of:

5050z/Olympus PT015/Sea &Sea YS90DX or Ikelite DS125

5050z/Ikelite Housing/Sea &Sea YS90DX or Ikelite DS125

or other configurations...

Anyone using a Tetra 5050 housing? Seems exceedingly pricey!

The PT-015 works quite well and the price is very attractive. I'd personally consider that the benchmark. If you consider anything else you have to feel like you were getting something for the extra money. The one thing the PT-015 lacks is hard wiring for the strobe. I suppose optics may favor the L&M as well. Personally I think the PT-015 is great.

I used a single Inon Z220 without a fiber with my PT-015 and it worked fine. Inon makes a less expensive strobe that is suitable called the Z180. I also like the YS90DX and think it would be a good choice. I suspect you could achieve TTL with DS125, but I had no difficulty getting macro exposures correct without it. The DS125 weighs more than twice as much as the others mentioned and uses a custom battery, but is quite popular with many of the members here.