Again do you see a Bride doing this on Her wedding day? Someone else will do it but not the bride the day of. To me it's tacky even if I wasn't a DJ. I'm bringing you a nice gift and this is whay I get for entertainment?
Again you are making it seem like this is much more complicated than it is. Is it going to be as good as if a professional DJ did it...Probably not or in some cases it might be better. The big risks are someone messing with your playlist. Almost anyone can program what they like on a playlist. Will it keep the crowd hopping? Maybe, maybe not but again let's not pretend that what she is doing requires a professional. She simply isn't looking for that level of service