Aren't there other "IM" packages you can download that do basically the same thing? I have seen a ton of different IM packages, most that do it via data instead of SMS. Most also give you access to user names or "pins" so you don't have to give out your phone number. Most send the most common files (although without a real file system it doesn't matter much on the iPhone). And sending location is possible with these apps as well.
The problem with any of these apps is that both ends have to have them. Same as the BBM app (if it existed). Unfortunately, few people download and use them, most just use the built in texting app.
BTW, built in texting app can do some of your features such as group chat, contact lists and multimedia files. Can't do read confirmations, delivery confirmation (is that really needed?), PINS, and location (which they should do).