I think you would be happy with either of them. They each have their own drawbacks, however. Of course, the upside to the Rupes is the long throw and the Flex is forced-rotation. You would just have to see which product would fit your needs the best. I`m sure others that own both or have used the machines would be better equipped (no pun intended) to help you.
I hope to help with the other product recommendations that you need as the build progresses.
Bookmarks