the dSLR barrier

the barrier to dSLR:
(for the following comparison i use canon G10 versus canon 450D)

price

• top of the line compact is about 600AUD, housing about 300AUD, total of about 1000AUD
  
• entry level dSLR camera with a kit lens is about 700AUD, housing with a port 1500AUD, total 2200
  

weight

• compact is 390gr, and the housing is next to nothing. total of 500-600gr.
  
• dSLR is 425gr without lens, lens is 250gr, housing 3200kg (ikelite housing for canon 450D), total of 4kg.

size

• a compact is compact barely there, can fit in a (big) pocket 
• dSLR needs an extra suitcase and an extra hotel room to fit in when traveling.

features

• a good compact has manual controls, macro, attaching wet lenses, video, all in one
  
• a dSLR is not very flexible (for entry level models), not flexible with strobes
  

So, from a relatively affordable, $1K 0.6kg small, manageable, easy to travel with, all around camera that can do everything at any time, you go to a very expensive 4kg, huge, not-so-flexible-at-all set up. so (entry level) dSLRs are much more expensive, terribly heavier, ridiculously bigger, horribly inflexible.

and that's good: if we take into account all those issues, the price difference between the top compacts and entry level dSLRs is the least of the problem. as for the rest, well, one just has to get used to carrying a closet around while diving. until technology manages to catch up.