One of the leaders in another guild in another guild I respect very much said to me, "people will become bored with 10 man and will want to do 25 man". I can see his point, but honestly I just don't see that. I started Kara last year in May and most days I STILL FIND IT FUN.
Top 5 Reasons I believe 10 man will surpass 25 man in WotLK
- Ease of getting 10 people together.
- Top end guild burn out
- Flexibility of Tanks/Healers/DPS
- Casual Friendly Environment
- PUGing FTW!!!
Ease of getting 10 people together
Just look at Wowjutsu.com today. At the beginning very few if any people showed up on the list except for the best of the best. With the growing desire of smaller guilds to do 10 mans, they have slowly filtered into Karazhan. Sure they weren't the front runners, but they got to go. With Attunements being lifted the accessibility of the 10 man content really drew people in. For my group I commonly refer to Karazhan as the "beer and pretzel's run". We all know it inside and out by the point and its just fun.
Every week I have 10 people signed up and 2-6 in reserve. Getting 10 people together is relatively easy for us. Now if we wanted to do 25 man, it would still be easier to run 2 x 10 mans than running a single 25 man instance. Getting 25 people together in a smaller or medium sized guild IS HARD.
Top End Guild Burn Out
I have a friend over in a guild on Shadow Council who used to raid pretty heavily. 3-4 days per week of concentrated raiding was their target. So they made some decent progress. Over time people started to burn out and get frustrated and eventually it just kind of dissolved. They still pull people in for 25 man content, but its become a real struggle.
Look at the news from the past year. Several very prominent high end guilds just completely dissolved. With this trend, and the guarantee that you will have a progression path in 10 man, its less likely that people will continue to "tough it out" in 25 man guilds if they are unhappy.
Flexibility of Tanks/Healers/DPS
Ok lets face it, the jump from 10 man to 25 man sucked for some classes. In 10 man, you needed 2 tanks, 2-3 healers and 5-6 DPS. To fill a 25 man you need 2-3 Tanks, 7-9 healers and the rest DPS. If you were DPS or Tanks you generally got screwed.. it took 3 10 man teams to effectively fill a 25 man raid. Which in essence means that 2/3 of your tanks got screwed and about 1/3 of your DPS has to sit out regularly. With 10 man you have a lot more flexibility to fill roles in the raid. 25 mans of the past seemed to need certain combinations. If you were number three elemental shaman you may see a run once ever 3 weeks. In 10 man you can probably get in every week if you want.
Casual Friendly Environment
I'm all for keeping things nice and laid back. 10 mans lead themselves to being a bit more casual. Its not to say that you can't have intense jaw dropping fights. Far from it, but for 10 man its not such a big deal to fill in a slot if someone has something come up. In a 25 man its more likely that you need a dedicated team of folks who always show up. Getting over the 25 man can be challenging especially if you have dedicated roles such as like the Hydross fight with certain resistance tanks.
10 man in its current iteration lends itself to being extremely friendly to swapping people in and out as needed. I'd imagine that trend will continue as you can't guarantee in a 10 man that you will always have a Shadow priest. So the fights can't be designed to assume anything.
Ok I'm not a big fan of PUGing myself, but I've read enough blogs and things from people to know it not only can be done, but IS being done. 10 man makes it extremely easy for people to PUG and get a group together vs tracking down 25 people who meet your needs for a 25 man.