Today, I just noticed something different on Mint Plus. 

Without the use of NorthStar Indoor navigation cube,  Mint Plus is able to navigate in my kitchen much longer when compared to the first original Mint. Mint Plus is able to mop the floor in a normal grid fashion (From bottom to top and then to the left or right) and covers almost the entire kitchen area without the assistance of the NorthStar cube! 

The original Mint is only able to work for a small area and stops itself after running for about 15 mins. Besides that, Mint Plus is able to complete its battery charge within 2 hours.

Thus, I will highly recommend Mint Plus if your budget allows!