I ferment in Sanke kegs exclusively... not to carbonate, but because it's way easier.
I built my own spunding valve using a tri-clover cap that was drilled and fitted with a compression fitting for a SS racking cane, a NPT fitting for a T that has the adjustable pressure relief valve and a gas-in post, and a third port for a thermo-probe. The thermo-probe in hind sight was not necessary... taping the probe to the outside of the keg works just as well.
The racking cane can slide up and down in the compression fitting (take the metal ferule out and use a rubber o-ring instead).
I never have to siphon, or lift.
I transfer directly from my kettle via pump to the keg already in the fermentation chamber.
It ferments there under temp control.
I don't have a gauge... I just "test" the pressure by releasing a bit to make sure it's fermenting, and the TC cap is well sealed to the keg.
I have a beer hose on the racking cane, and a beer-out coupler on the end of it. I also have an adapter that makes it so I can attach a picnic faucet to the end of the beer-out coupler.
I can take samples under it's own pressure this way.
Using just the beer-out coupler, I can transfer to cornies by connecting directly to the beer-out post on the corny.
It can't transfer under it's own pressure... that's why the gas-in post is important for complete final transfer to cornies.
I pre-purge the corny with Co2, then fill. The fermented beer never see's the light of day or the oxygen in the air until I pour a glass from my 3-faucet beer fridge.
My keg of choice for fermenting is 1/4 bbl (tall skinny 7.75 gal.) US-D Sankes.