Every holster design involves compromises among the four basic factors of comfort, accessibility, security, and concealability. Whenever one factor is emphasized there will be compromises in the other factors. If there were such a thing as the "perfect holster" that would be the only holster design made for all purposes (just as there would be only one handgun design offered for every application).
IWB-style holsters emphasize concealability, keeping the bulk of the weapon inside the trousers, thus offering greater latitude in cover garment selections. The trade-offs are usually in comfort (for many folks) and accessibility (particularly the ease of re-holstering).
These are the facts, period. There will be varying degrees in the compromises experienced with any IWB holster design, but such compromises will always be involved.
Based upon the orders that I receive it appears that about 30% of all customers carry IWB-style, and I offer a couple of different IWB-style holsters to accomodate those needs.
Requests include the full range of handguns from very small to very large, so I know that people use this carry method for everything from the smallest semi-autos to the largest magnum revolvers.
When I receive inquiries from people considering IWB-style carry I always try to point out the compromises in comfort and accessibility, as well as the possibility that larger sized trousers and belts may be required. Frankly, I do not encourage IWB holsters for people without experience with them because I know there will always be a significant number of them who cannot tolerate IWB-style carry. I also receive positive feedback comments from customers who regularly carry the largest semi-autos and N-frame revolvers in my IWB holsters and love them.
I also receive inquiries from people concerned with ease of re-holstering, specifically one-handed re-holstering. I always try to recommend any holster style OTHER THAN IWB for those with such concerns.
One-handed re-holstering is a legitimate concern for law enforcement applications, as officers may need to rapidly escalate or de-escalate their tactics in certain situations, and may also find themselves involved in suspect control situations while also having to assure weapon retention.
For most of us, however, the purpose of carrying a defensive sidearm is for defense against violent crime. In such situations re-holstering the weapon is about the last possible consideration.
It seems that many defensive handgun training programs stess a number of things, such as one-handed re-holstering, thus convincing lots of people that this is an absolute requirement. I suggest that it is nothing more than one factor to be considered in light of all the other factors pertinent to each individual's circumstances and requirements.
Many public and private ranges prohibit cross-draw holsters for obvious range safety reasons. This does not mean that cross-draw holsters are not a perfectly good choice for some people and applications. I know of many folks with range-of-motion issues, shoulder problems, etc, that are well served by cross-draw rigs.
What works well for one person will not work equally well for all people. I suggest a careful evaluation of your personal requirements, physical abilities, training levels, usual wardrobe, typical activities, and other considerations when selecting each item of equipment. Most of us will try several carry methods before we settle on one that best fits our needs.
Best regards.