Hi! I've started to playtest these two strings myself. Have played with the Cyclone for 3 hours and the Pro Line X for only 1 hour, so I'm not that familiar with the strings yet. I also strung the Cyclone at 55 lbs and the Pro Line X at 51 lbs.
Feel: They are both pretty soft for polys, but Cyclone feels more crisp, while PLX feels more muted.
Power: Pretty equal. Both are medium powered polys I'd say.
Spin: I noticed more spin with Cyclone
Control: Depends on your strokes I guess. PLX felt very nice for flat shots while you get that extra margin on topspin strokes due to Cyclone's spin potential.
As for how long they hold playability, 1 and 3 hours of course isn't enough to tell you anything about that, but it seems like PLX gets a lot of praise for it's ability to hold tension fairly well.
This is just my own view after having just started to test the strings
Bear in mind the tension difference I strung them at.