Hi deanyel, your mechanic is only partially correct concerning the price of 722.6 parts. True, the valve body and control unit will cost about $1500 but the majority of these transmissions can repaired for far less. With accrued mileage the tolerances can increase to the point where it affects the shift quality. The tolerances can be adjusted during re-assembly by using the correct size retaining snap rings. There are six of them and they cost around five bucks each. The one way roller clutches may be the most common problem and cause a variety of problems. These can be replaced as well. There are two of them and they cost about thirty bucks each. I've seen various internal seals fail as well. The seal kit for the complete transmission only costs about sixty dollars. The valve body can be dis-assembled and thoroughly cleaned as an option to replacing it. In the early days of the 722.6 this was the standard procedure and it was usually successful. Of course I've also seen my share of catastrophic failures as well. In these cases re-building was not an option. I've re-built both 722.3/4 and 722/6 many times and I can say without hesitation that the 722.6 is much simpler. As to which one is more reliable is a matter of opinion.