While the need to step through temperatures is generally unnecessary in modern brewing, the ability to target, hit, and maintain a certain mash temp is a very useful effect of the approach you mention. In addition, it has been proven that creating a truly homogeneous condition in a mash tun via mixing is VERY difficult...if not impossible. It turns out that it is far easier to move and mix the liquid than it is to move and mix the solid media. So moving to a pumped system will provide that benefit.
Then one thing I would caution is that the system needs to include good measures that avoid heat loss. The system needs to be capable of maintaining that target temperature without resorting to overheating the wort in the kettle. Remember that the enzymes that are working on the wort are in the liquid, not the solids. If you overheat the wort in the kettle, you will damage or alter the enzymatic activity.
Finally, with the system you suggest above, it should be fairly easy to perform a mash-out temperature step that can add a couple of Brix to the wort strength and that can improve your overall efficiency. Mashing-out is a PITA for most homebrewers, but your system could make it much easier and advisable.