When you have to balance job security and life security, it's best to consider all the carry alternatives rather than focus on the advice of those who don't need or even care to. They aren't forced to accommodate deep carry to prevent job loss and a difficult rehiring process, which should be an indicator of just exactly what they know about it.
When your work requirements force you to wear a tucked in uniform shirt, be in close proximity with other workers who will see you bending, stretching, lifting, and reaching tall shelves, or work in close proximity with retail customers, printing becomes a major issue. "Lumps" might be cell phones, as those could be equally proscribed by workplace rules - but not in IWB holsters, or underarm carry. Unless you are known to be wearing an insulin pump, don't count on casual observers mistaking a lump for some other innocuous device. It's a lump that doesn't really belong.
Lots of casual IWB carriers who just "go about their business" should count their blessings, because in an active retail environment, nothing they enjoy is allowed - even carry. Most companies don't allow weapons in the workplace, and there are plenty of cases we fight as First Amendment users to restore their rights and employment. I find it naive at best to suggest anyone just do whatever they like in the obvious face of corporate rules requiring their employees be disarmed, or be unemployed.
That's exactly why deep carry holsters exist, and the pooh-poohing of those who do everything but carry open isn't the best source of recommendation. They aren't able to do anything to prevent your employer putting you on the street. The first rule is to protect YOURSELF, and it's up to you to balance your security needs with your workplace rules. It's hard to support a spouse, family, or make money for your own needs and desires when somebody else's advice gets you burned.
If you consider the risk of actually being endangered with lethal force at the job, and the risk of losing that job, and determine that trading off speed of access will allow you to keep working there, then that's your choice. Most of us aren't confronted in our workplace with gunmen intent with killing us - despite all the notorious news. Most often, if you are, it's a robbery, do what they ask (up to a point) and give them the cash. It's pretty lame to acknowledge you weren't aware of them in your environment and made no effort to counteract their presence - but many do.
There's really not that much difference in carrying IWB or smartcarry - it's basically a method of keeping the butt of the gun just below the belt line. If you wear pants and a belt that tightly, you would have to make exactly the same change as IWB, size your pants for the rig. Training - same - you would have to move any garment out of the way, in this case, pushing the belt away to reach the butt is just part of the routine. You wear a smartcarry holster over the shirt tail, it's not in the way. With practice, it should come down to a fraction of a second difference. At that point, accuracy of fire becomes much more important.
Then you can let management decide whether to continue your employment, which they likely won't. But you will at least be alive - or more likely so, which is the intended result, and perhaps some coworkers might thank you for saving their lives. At least if you are working now, you are more employable, and can move to a job that is less restrictive of your rights - rather than out on the street with a "man with a gun" reputation that keeps you unemployed.
It's up to the individual to assess all the risks in their environment, and second hand recommendations should be considered in exactly that light. A well rounded and realistic appreciation of ALL the factors will have a better application than an off the cuff response that "all the big boys do it this way."
They worked their way to a privileged position, not all of the rest of us have those rights, and it's pretty short sighted to think we do.
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