I have an Apex and 2 gen 2 Waveline pumps (a 4000 and a 6000). We have been told that an updated controller will be released for this pump that will allow it to interface with an Apex variable speed pump VDM module. Once it is released, I will need to buy both the Waveline controller (probably around $40), AND the Apex VDM Module (99) if I want to be able to control speed from the Apex. I was excited about it at first, but after realizing the cost and getting used to the pumps I realize that I just don't need it.
The people that i could see benefiting from it:
a) If all your flow was from DC pumps on closed loops and you wanted to vary the speed.
B) if you had the whole system on battery backup and you wanted to lower speed during an outage to prolong battery life.
Note: Don't take this as a negative against DC pumps. I love my wavelines for many other reasons (runs cooler and quieter, and uses much less power) and will never order another AC pump for any installation where a DC equivalent is available.