10 characters worth of gear, 5 man farming instances pre Karazhan, 5 man farming rep, then 5 man heroic farming instances pre Karazhan, then maybe if you've done that, you'll get a taste of what 10 boxing will be like in Karazhan.

If you can't handle 5 toons for heroic instances, many heroic instances, then yeah you got a chance at doing Karazhan, very small chance. Be successful is different story.