I have customers with the 1054 and 1057. Never had a locking problem. Even the 1055 seems to work really well under big power.

The 1056 is a good converter, but with twin power we ran into the problem you guys are having. Swapped those out for 1054's and problem went away.

The 1058 and ATS converters seem to have this problem more than anything I've seen. My theory on the 5 disc ATS there is too much fluid in between all those clutches and it not being able to apply fast enough because of the slower fluid removal. The 1058 has been a PITA forever.