Great questions. From the list of your three choices my pick (and seemingly the most popular) would be the CV 457 Varmint MTR. I am in the same stage of decision as you are. That said, I am leaning to a Bergara B14R 22LR platform. You can buy just the Bergara barrelled action. It's based on the Remington 700 so there are lots of upgrades and extras available. The B14R comes with a stock/chassis that has an aluminum internal frame surrounded by the polymer. I have swayed back and forth between this set up and the CZ457 for sometime now. I think the CZ is a great platform from the research I have done. I feel I would be very happy with that choice myself.
So, sometime in the last couple of days I stumbled across a CZ457 Varmint MTR in stock somewhere online. I went back through my history but can't find the site. I am left handed so, unfortunately, that stock is not really set up for me grip wise. Best of luck on your search and decision making. I feel your "pain"

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Also, never mind the troll. I wish this site allowed a complete block of a member rather than just "ignore". It's unfortunate that some people are so sad with themselves that they feel the need to try to bring a fight with everyone. When someone tries to do this over a post on a community forum it really speaks volumes for their character. In the end, they are just another username on my ignore list!