Sara, i have used both the regular electric mixer and the kitchen aid one. Honestly, i was blown away by the KA, its just so powerful. I got one from my parents when i got married and tht is one of the most useful presents ever especially since i love baking so much. I also make doughs in it for pizza and even for roti. Some recipes require you to beat teh dough for longer periods of time and the KA makes it easier to do so (for example some bread or brioche dough).
That being said, if you are not a regular baker or cake decorator, you may not use the KA much and hence would be a waste of money. It is also super heavy and requires some counter space so if you dont have the space, you will find it a chore to take it out/pack it up again for one time use. KA mixer is the only appliance that i keep on my counters.
To clean the tips, i have this little brush, a mini version of a baby bottle cleaning brush that i use. Alternatively, the dish washer also cleans them out if the icing isnt stuck dry.