I don’t understand that perspective- it has solid sides, the wort is pumped from below to on top then flows down past the grain which should improve extraction and mix temperature. There is a small dead space between the grain basket and the kettle side but that can’t add up to much, and the fluid level there will be lowered during recirculation.Yeah, this is true. I don't get overshoot but yes the temp will drop 4ºC before the thermostat kicks in so your mash temperature must be varying somewhat. It's a niggle but my beer still turns out well.
Same. A pump isn't essential at all, but I wouldn't go back.
I also remember now another I ditched the grain basket in favour of a grain bag...
The basket has solid sides, not perforated. So even with a pump the liquor there is not recirculated. If you take a gravity reading from the top of the grain bed in the basket it can read artificially high.
Simple solution could be to raise & dunk the basket a few times during the mash, but to be fair even if you just leave it your mash will work fine and you can still make great beer.
I don’t know if the MashFest is any better or worse than similar all in ones - but it is sometimes much cheaper.