Slow Mohs procedure on toe with melanoma in situ?

Its difficult to comment on your situation without seeing the area in person and reviewing the pathology report, but in general your melanoma appears to be in situ which is very good. The reason your dermatologist is suggesting slow Mohs (which is not really Mohs surgery but uses the concept of Mohs to minimize removal of normal skin) is to get the melanoma out without taking out too much normal skin. If done by a well trained surgical dermatologist this can have as good a cure rate as wide local excision. I routinely use this option on the face, hands and feet for early melanomas and favor it over wide local excision. 

"Slow Mohs" is primarily done when a physician doesn't have an in-office histopathologist and must send every level out to a lab for examination to examine the margins of the cancer being removed. When traditional Mohs are performed we do it in-office with a histopath here so that each level is examined and the patient doesn't need to return again and again. I'd try to find an office to treat you with a traditional Mohs rather than a "slow Mohs". My assumption is that you perhaps aren't going to a board-certified Mohs surgeon..... "This answer has been solicited without seeing this patient and
cannot be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."