I have done both. I can speak from experience that three wheels are more stable and handles much better then a add on kit. Add on kits also eat up rear bike tires in a hurry. They also don't stop well in a panic stop. They will skid much further then a 3 wheel trike with full rear brakes. Been there, done that. Very scary! Feels like your on ice. However, you do have the security of not having to worry about laying down your bike. That's about the only plus for the add on kit. But if you can't afford a real trike, and you want to continue riding, then its really the only alternative. Whatever it takes to keep the wind in your face.