What makes the Nauticam and Recsea housings worth the extra money? I've always had great luck (knock on wood) with Ikelite housings.
I don't own RecSea products but owned a few Nauticams housing.
Ikelite if for RX100 size and where the lens port is not replaceable, should be OK.
Ikelite for DSLR size or Sony NEX7 kind of complicated TriNav dials, I won't even consider.
Aside from what Nemrod explained, to have DSLR where for various ports , one will need a few ports for different lenses, the way Ike secured the ports with 4 screws :
Ikelite Underwater Housing for Nikon D800 & Nikon D800E Camera ike-6812.8_2.jpg
.........is a joke.
Plastic is not a material suitable for repeated abuse from threading a screw in and out. Let alone comparing the beautiful & secure way a Nauticam housing changes its ports.
A full frame DSLR lens like Nikor 14-24mm cost USD1,800ish.
Nikon 14-24mm f/2.8
Not to mention the cost of the port and the extension.
Cheap housing body like Ike for expensive DSLR is a waste of money and not a savings.
The approx US$1,600 to US$2,000 savings compared to any good alu housing in say a D800 category, is of no value in the end. You pile up the collections of lenses, ports and all other UW photo gears, the housing main body price difference will not become significant portion of the overall cost. I don't need to go in details on how engineering of buttons/dials/triggers and ergonomics of a good alu housings compared to an Ike. Spend an hour in a shop that carry an Ike and a Nauticam and/or Aquatica for Nikon D800 or Nikon D7000, place the camera inside them, play with the camera controls, change the lens and the ports while at it..........you will understand what I mean. Operational feel is something hard to write about, experience it yourself will be best.
Ike ports can and have dropped of from main body during a dive, if it has gone thru many repeated port changes. As I said, plastic is not something you want as a female threaded base for a stainless steel screws holding a heavy and precious port and is part of the waterproof integrity of the housing.
Ike has its place but with today's 5 axis CNC machine being much cheaper than 10+ years ago, aluminum is the way to go when the camera of choice can have lens change, hence a port change.
Company like Nauticam actually made today's alu housings prices much cheaper than 5 years ago.
To see and use a small camera like S100 and RX100 in an alu housing with full controls is so awesome !!!
Luck is one thing Reef, but precision and well constructed alu housing is an engineering art in itself.
For toughness, alu housing can't be beaten by any plastics.
Have fun shopping.......