The one issue that I have with combo based DoTs or upkeep buffs is that they push the job towards a fixed rotation, like PLD. This reduces your flexibility to make resource management decisions on the GCD. This is one of the reasons that I recommended a free-form combo system similar to MNK, in that you're not obliged to follow through with any given combo to the end.

Procs are another good way to differentiate resource management jobs from fixed rotation jobs, especially when they lead to variable resource gains. One of the nice features of Blood Price was that it did lead to slight variations in your resource totals, such that you generally weren't at the same MP/blood totals at a given point in the fight. That tends to keep things interesting.

Everyone remembers Scourge fondly for the animation, but most players struggled to maintain adequate Scourge uptime back in Heavensward. I'm not sure how well the current playerbase would fare with it.