I currently have an old, unnamed, crank, gliding clamp stringer that must be 15+ years old. It was purchased used, and I have had it for 10 years where it was mostly kept outside in a shed during spring, summer, and fall near the Illinois-Wisconsin boarder, which is not great for maintaining metal pieces. This was done to allow tennis students access to the stringer without needing a key to the building. I have a kid now, so I don't have an hour+ to putz around with my current machine, and the machine will be kept inside at all times.
I'm trying to get the most accurate string job, a reduction in time while mounting, and a decent price with quality also thrown in the mix. It's a long list. Gamma SC models fit the reduction in mounting time while the X-ELS and Progression have 4 arms that need to be put into place individually. Self centering will allow for the most accurate tension and also reduce time of mounting.
I originally looked at the X-ELS and Progression II and thought I read something about linear gripping vs rotational gripping and some issues with Gamma's rotational gripping, which is why I wanted the WISE which has the linear gripper.
The Eagnas Flash 930 is essentially a Gamma 6004 clone, but obviously cheaper, and also on my radar. Again, reviews have been iffy about Eagnas/Maxline. Specifically the poor reviews I have read dealt with a DOA electric tension system, which is not what I'd be getting from them.