If it requires finesse to milk a bong, then the Hopper is NOT working properly ... whether it is acceptable is up to each individual, but if one can't milk a bubbler, and can't cache a bowl in 1-3 hits, then either you have horrible lung capacity and that is the issue, or the Hopper isn't right.
The most frequent problem with Hoppers for me is that the heater seems to "give up". On a properly working Hopper, it will continue to thicken the vapour throughout the draw (after the initial 5 sec or so heating of the load). When they are performing poorly, and requiring many pulls to finish a bowl (and even then not vaped evenly/completely), it's like the heater starts out ok for the first few seconds, and then "gives up" ... since I can only get the heater to put out decent output for ~5 seconds, it takes many draws to finish a bowl, as just when it is getting going, it stops producing enough heat. (this is what is happening currently with my Ti .. my SS is working properly except that it goes to flashing reds often just before the end of my draw, and it gets too hot in the back-end, so presumably there is a poor connection somewhere causing a voltage drop that is resulting in excess heat ...)
Anyways ... I personally have no interest in a Hopper that takes 6-7 draws to improperly vape a chamber ... I have many other vapes that will work better as a session vape then the Hopper ... as an on-demand heavy hitter, like a desktop, that's portable, Hopper stands alone; so if my Hopper can't be a heavy hitter, and I have to "finesse" it ... then it's not filling the spot in my lineup that it is intended to ...
Grind style, moisture content, etc., etc. can all play a part for sure ... but a properly performing Hopper is extremely tolerant and will do as well with herb as any other vaporizer (portable or desktop) in terms of quick/massive cloud production. If it isn't keeping up with your heavy hitting desktops, and can't be used as effortlessly, then you are fooling yourself if you think it is working properly. Is the way it's working acceptable to you? That I can not determine; but it is definitely not working right.