Hi Beaker, and welcome.
Im running a Watlow with the thermocouple mounted on top of the boiler. The standard brew temp is set at 108°, although with my current beans, Im getting very nice results with a temp of 109°.
Not sure about your comments re flash boil, but this doesnt seem to be an issue, flavour wise, from my machine. I suspect that by the time the brew water reaches the puck, it has dropped to the required temp. If your brew temp is too low, you will not be extracting the full flavour profile from your beans - so that may account for your lack of flavour.
As far as dosing goes, I use a double synesso basket which I half fill, tap down then overfill, sweep off level with my finger, and tamp. This consistently packs down to the level of the ridge in the basket, which I find is just right.
Some food for thought...