It's upto the founder as to what they allow in their room. To each their own, providing it is legal. A mIRC connection can, to the untrained eye fool someone else into believing that the connection is infact a java user, however to the trained eye it's simply not possible. CR provides opers with many ways to ascertain non-genuine java connections, needless to say, I am not going to list them here as they are trade secrets.
As for CR Java v's mIRC, well both can be 'annoying' as both support popups and channel CTCP and both can flood a room with either event. CR's Java applet also has smileys and miscellaneous avatars which can, to some, cause a flood. It's not the point though. If someone wants +j then I think it is perfectly reasonable to expect that users will respect the founder's wishes.
