I wouldn't worry about the Canon OEM UW housings leaking at a depth in the 100 fsw range. I've taken mine down to a small airplane wreck that's at 135 fsw. The camera worked just fine. I have a buddy who does some technical diving and he's taken his Canon housing down to about 150 fsw with no issues.
In my experience, the one issue with the Canon housings is that the buttons may start to stick at greater depth. A couple years ago, I missed out on taking a pic of large, inquisitive mola mola because my camera housing buttons got "sticky" at 125 fsw. To a large extent, the sticky button issue can be mitigated by periodically removing the button shafts and re-lubing the button o-rings. Here's
a link to a webpage that describes step-by-step how to do this straightforward DIY maintenance. Since I started doing this maintenance, the housing has continued to perform very well.
An additional tip is that after you do this maintenance on your housing buttons, do a test dive during which you substitute a paper towel or tissue for your camera inside the housing. Then, when you get to depth, operate the buttons as if you were using the housing to take pictures. Essentially, it's a real-life pressure test. If a button leaks, you'll be able to see it and fix it before you risk damaging your expensive camera.
BTW, since you're a relatively new diver, I'd recommend that you get some formal deep dive training or find a more experienced dive mentor who can introduce you to diving in the 100 - 130 fsw range. It would be wise to learn about gas planning/management, nitrogen narcosis, and carbon dioxide retention before doing dives in that range. Also, make sure that you have excellent buoyancy control before messing around with an UW camera. You'll get better photos, have much more fun, and dive more safely when all of your other dive skills are up to snuff.
Have fun out there...
