How does it go?? Sorry for going a little off subject curious to find out whether they are worth the $ my club is looking to upgrade their 1970s Bola 
If you mean the Bola then it goes as fast or as slow as you want. Not sure I get what you mean by 'How does it go' ?
If people are really interested in improving (and speeding up that process) I personally think it's one of the most important bits of training kit. I know some may disagree etc but just from my limited experience in 2 winters it's took me from someone that just saw the ball and hit it (heaven know's what my feet etc were doing) to someone that actually starts to play 'properly' and can occupy the crease and play all around the ground as I've been able to work on the 'weak' shots and so turn them into decent shots.
I genuinely believe although it's not the be all and end all if a club really puts the time and effort into working with their players individually on something like this there would be a hell of a lot better batsmen around.
To prove my theory i've taken a guy that's 21 and been written off by the club as 'nothing more than a hitter who can play the odd good innings' and over this winter working with him he's turned himself in a good batsmen. Playing the percentages, picking the balls to play the right shots too whilst still maintaining that timing and power he had to hit big. Hopefully if he chooses to stay with the club he can go in and basically show up some of the 'reputation' players (which tbh he'll easily do). It'll be itneresting for me to see what runs he gets over the season but more importantly does the club see it or are they too stuck with the reputational players (I suspect they are, clubs don't seem to like trying new players and moving out the dead wood)