I've used both.
Heres my take: if you want more precision and ease of use/simplicity...go ehydro.
If you want less precision, more complication with less ease of use /simplicity but more power...go power reverser.
In my opinion if you are running out of power with the ehydro, the you bought the wrong tractor in the first place. With only a 5-10% power loss with the ehydro over the reverser, if you are living on that fine line between the tractor not having enough hp because it bogs down then you need either a larger tractor or same platform but a bigger motor. Example 3320 may bog down, but you could upgrade to 3520, 3720 or 4020 series.
My vote hands down: ehydro