...but shouldnt that reguator hold up the same as a 400 reg at normal conditions?
It depends on what "normal" conditions are.
Let's take mountain bikes, for instance. On a nice paved trail at a state or national park, just about any "mountain bike" will move you from point A to point B. But I don't just want to ride on nice paved trails. I ride out in the desert 20 miles from the nearest help and have only the cactuses and rattlesnakes to keep me company. So what do I want? I want a bike equipped with quality components that can take a serious beating and still perform. I want rims that won't "taco" or deform when I slam a rock. I want derailleurs that can get filled with dirt and sand and keep shifting smoothly. I want brakes that can finesse me around narrow switchbacks. I want a suspension system that will absorb the bumps in the trail but won't launch me into the air. Plus, I want a bike that is light, so that when I have to carry it around a cliff I won't have difficulties. These are "normal conditions" for my riding, and having broken bike frames and components under those conditions, I had to rebuild my bike with higher-end, "bomb proof" components.
With diving, you have to consider the same factors. If you only plan to dive on vacation in nice, shallow, warm waters escorted by a DM or Instructor, you probably don't *need* equipment of the same "quality" as someone who's doing more technical dives.
I think the real question is how far you intend to push your equipment. For instance, take the regulator you mentioned and a Scubapro or Apeks high performance reg. At the surface, there will be a difference in the way they breathe, but it won't be the sort of dramatic difference you might expect. However, suck a couple thousand PSI from your tank, take the regulators to depth, and you WILL see the difference.
It's the same consideration for any item. BCD? Well, do you plan on penetration dives where your equipment might be subject to abrasions, snags or punctures? During graduate school and law school, I sold computers to finance my hobbies. Invariably, most customers would say that they only wanted a computer for word processing, balancing their checkbook, and maybe e-mail (which was a new thing they really didn't understand). My response to those customers was "It doesn't matter which computer you buy, then, because all of them will perform those functions." And then I started discussing other possible uses and whether those things were of interest to the customer. Once the customer had determined what s/he REALLY wanted to do, then we were able to find a system that worked for the customer. Of course, the price of the machine increased as its capabilities increased.
There is nothing wrong with having a budget for equipment purchases. Every financially astute person tries to adhere to some kind of budget, even if you have plenty of money to spend. My advice is to decide what kind of diving you plan to do, find out what kind and quality of equipment is necessary for that kind of diving, set your budget, and then buy the best quality you can for the money you have.