to help with channeling issue, you could go for the geeky way of using an Aeropress filter on top of the puck.
https://www.baristahustle.com/blog/e...he-coffee-bed/
For medium-dark espresso blends roast coffee (e.g. old school espresso from 49th, Equinox Espresso from Agro, Eastside from JJ bean), I find the traditional 1:2 ratio to work best for milk based drinks. For more delicate SO espresso, I usually go for a 1:3 ratio to stretch out the flavour profile, anything less and it is way too overpowering (e.g. too acidic, metallic mouth feel).