Who disagrees with DIR and why?

[FMT]

Seriously Dean, if you check out (many interesting sections there) and read the Fundamentals of DIR book you will find many answers. After that I'm sure you will still have a few questions or may not have the why for some others. Then ask away. I think you should ask those questions in a NEW topic of this forum though since your purpose is to get convo going not to focus on the "I hate DIR and here's why."
T

Here is JJ explaining a few things as an intro:
Divers entering advanced training for the first time or considering furthering their education are often faced with a complicated range of difficult choices. Individuals interested in the Global Underwater Explorer curriculum will find this section indispensable as it will familiarize them with the type of equipment used during GUE training. Undoubtedly, individual opinion may vary about the nature of equipment and where feasible, GUE has allowed for a variety of generic items. However, our representatives do not believe in the "anything works" mentality. The GUE recommendations about gear configuration and selection represent the opinions of leading explorers and professionals but should not be construed as an attempt to represent other equipment choices as necessarily unsafe. While GUE recognizes that equipment style and choice are personal determinations, we present a standardized set of gear recommendations to familiarize interested individuals with a system utilized in over thousands of hours in extreme diving conditions.
Students participating in GUE instruction should come to the classes prepared to modify their gear configuration to meet GUE guidelines.

While nearly any style of diving equipment can be feasibly used in a GUE class, the GUE curriculum has been structured to instill divers with the same technique and ability found in world class explorers. While we recognize that this level of expectation is beyond the type of diving that many students will participate in, we believe that individuals are seldom overly prepared for a given diving occasion. Opportunities abound for individuals to enter a more liberal-style curriculum allowing for a wide variety of individual choices. However, the GUE curriculum is structured with the assumption that participants are not threatened by a conviction that one style may be more effective than another.

GUE representatives are not attempting to label other techniques ineffective or dangerous, but they would be irresponsible not to feature the highly effective and popular style used by all of our members. Regardless of an individual's chosen path, the gear modification section of any GUE class will be very educational. The information contained within the course outlines for open water, technical, or overhead diving is tailored to the GUE curriculum and divers training with other organizations should consult the recommendations particular to those organizations. While most of the general requirements should be very similar, individuals will find other organizations less explicit in the type of equipment to be used. Divers not certain about their level of dedication may be interested in training within another curriculum. These individuals have an array of options and are encouraged to review their opportunities.

Regardless of your chosen educational path, we wish you all the best in your future diving activities.