Based on the MSRP of the Liquidator, I have to assume, with all of the enhancements they've made, that this item will be up in the $300 range or more. It looks much more advanced than the liquidator. Based on the performance reviews and reliability issues associated with the the Liquidator, I think I would go with a tank and a Stenner. I have about $350 in my setup, and I see it as being far more reliable and consistent than this design simply because of the physics of how it works.
As for the variable speed pump, I think it would work (based on my understanding of how the Liquidator works). The issue is that you are going to get different chlorine dosing based on the speed the pump is running. If you always run the pump on the same schedule, you'd probably figure out the dosing with some trial and error. But, if you don't, you'd have to keep that in mind. And, as mentioned, if it requires more high speed pump time to properly dose the pool, you lose some of the benefits of the low speed energy savings. I guess you could install two of them and have them run in parallel, but at what initial cost?
It does have the benefit of not requiring a power source. So, if that is a consideration, it may be an option for some people.