I string a fair bit of squash, and own a Prince Speedport Black. The ring causes little to no friction, so I don't think you need to adjust the tension too much when stringing.
I try to do top-down for the crosses. On most squash I have come across (Tecnifibre, Black Knight, Oliver), I almost always do an ATW pattern. It seems to help, especially on the open throat racquets. Seems to keep tension on the bottom crosses better, as opposed to bottom-up.
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