Even with the check valve at the bottom of the hose, it DOES make a difference. Each stroke has to overcome the previous stroke's pressure to defeat the check valve. This gets proportionally higher and higher as the pressure rises. i.e. the piston is higher up it's stroke when it does overcome the stored pressure. This means it is displacing even LESS volume each time, while trying to raise the pressure in an already largish volume.
Basically, yes, you CAN achieve the same pressure reading with a long hose, but it will take waaaaay more kicks/strokes than a short hosed(small volume) unit. You will hit a point where the needle is rising but at a rate that seems like it has peaked and you will notice that the needle peaks and then settles some before 'storing' a reading.
Ever filled a portable air can? You know how it takes more time to get the last 20psi in it than it does to get it up to 100psi from 0?
Same effect.
After talking about this last night here I spent some time at my shop testing this very concept today, plugging my echo guage into every hose available in my bike/sled shop and the next door auto shop, with hoses from cheap units and hoses from that $216 snap on kit. My echo guage has a check valve on the guage head and one on the plug end of each of its' hoses. I used a 440rotax powervalved sled engine(twin-220cc per hole) with no exhaust pipe and carbs removed. With the stubbiest of hoses(an inch of hose between hose end connectors) I saw 185psi in two pulls. With a 25" hose w/o a check valve on the hose I gave up at 136psi after 15 pulls. With an 18" check valved hose I achieved 185psi after 9 pulls. Each pull on the sled starter rope equaled 6-7 crank revolutions.