Hi there. Unfortunately I can only give you advice from my limited experience.
Pro Jumps/Powerisers are great fun and excellent exercise. Yes they do take some time to get used to as the technique is slightly different to normal walking. It does require balance and if this doesn't come naturally, learning to walk on them will be long and arduous. However, once this is mastered there's no stopping you.
Avoid the grass where possible, I have found even on dry grass I have felt the rubber pads slip. I feel safer on a hard surface but knee, wrist and elbow protectors are a definite must. (A helmet wouldn't go amiss either).
I have picked up the technique really quickly and my power along with my weight (13stone) will now mean I will buy a weight or two above what is recommended for me so that I can jump higher and allow them to last longer.
This is by no means official advice, I am only giving you my personal perspective so ultimately the decision lies with you.
Hope this is of some help to you..
Toby