I've been using the xi5 for about 3 weeks now. It's about the same motor as the MK except the anchor feature is MUCH more accurate. It holds you within about 5-6' whereas the MK held within 10-12' or maybe more.
On the contrary, being more precise means it's twists and turns more to keep you situated, especially in fairly calm water cuz it sometimes "overpulls".
Overall I like the MG over the MK.