As a Raid Leader of both and the only guild, on at least my server, to transition from 10 -> 25: The stress level and amount of work each night is DRASTICALLY reduced with 24 other people than with 9 others. And to me the fights and sense of accomplishment are FAR more epic.
I am the raid leader and strategy creator for my guild and have been for several years - right back to BC. I even write guides for internal members which when complete I usually make public - such as http://enigma-nagrand.com/phpBB3/viewtopic.php?f=82&t=3545 so that others can benefit from our experiences.
I can only make that comment make sense if you are not doing progression in that 25 man raid setting. When I hold that statement up to our 300 wipes on Yogg Saron, 400 wipes on Lich King Heroic and then compare that to the encounters mechanics as they weere designed for 10...... Well as Robokapp said above, there are worlds in between. And I am not talking just about tuning.
Additionally, I share the burden of running this guild with another GL whom we have equal responsibility but different tasks. He is the recruitment specialist. Without having the two of us together we would have collapsed months and months ago and no longer exist because the combination of pressure and stress in keeping this format alive does not hold a candle to the 10 man format.
We choose to do it because both of us are of the same opinion - that it is 25 mans or we quit. In fact we have so little interest in raiding 10 mans that should 25 mans ever end, our guild would end right there. Most of our players in guild are of the same opinion.
I recently pointed out that using the only numbers we as players have to estimate - which of course have to be taken somewhat skeptically - show an approx 30% increase in end game raiding numbers from BC > WotLK. The transition from WotLK > Cataclysm saw an approx 50% reduction in end game raiding numbers.
We are at present, in Normal and Heroic content at a lower participation level than BC - and it boggles my mind that people seem to think this is a good
I just recently had an argument on this topic in our internal forums with a member who actually likes the strength of the choice in 10 mans being there and disagrees with me so I do understand why people are so passionate about the 10 man format. What I still cannot get over, no matter how many times people state that having 10 man as an option is a good thing is when looking at total raiding attendence and seeing what that transition cost the game.
Remember this is a game
therefore it is designed to facilitate fun
in whatever way that means to people. Bringing the 10 mans up to equal par was an attempt by Blizzard to be fair and to give unprecedented access to top level raiding by allow smaller formats to compete "Equally". Retrospectively however, this idea turned out to cause half a million players to leave raiding entirely - not go 10 man, just stop.
Why? Because of a critical lack of consideration for plain old human nature. That is, if you provide two "fun" options where the rewards are the same, but the challenge to get them is skewed in one direction then we as human beings will gravitate to the easier of the two paths. And that is exactly what happened.
I suppose one of the reasons I get so irritated is that equalizing 10 mans caused 90% of the 25 man population to disperse but for 10 man raiders this apparently is acceptable - but any effort to put 25 man back on equal footing is bad because - oh the horror - some 10 man raiders may go back to 25 man.... There is a great big whopping double standard coming from some 10 man raiders here.
Also, much of these tasks are distributed amongst more than a single player in any well run 25 man guild (they would have to be....). The point still stands it involves more logistics.
Just on this topic, we tried having officers and each and every time we had issues with them. It didn't matter if we had been playing for months together, they became an officer and suddenly they changed. We decided some time ago now - like 12 months or so - that we would no longer have any officers. My Co-GL and I run all aspects of the guild together as ironically, it is less stress and drama doing so.