In the end, the secret was in tuning the printer and preparing the bed then, and most importantly, printing with the right filament - a consistent filament, smooth, printed at the right temperature. A filament that would print the first layer as well as it prints the last. Filament that can print a smooth layer right on the bed then make a straight, smooth line on support. They had tried many different brands... the problem, they found was consistency. Cheap brands are often good at printing some things some times... but if you test with a 30 minute print time then start a 9 or 10 hour job do you have the confidence to walk out of the room? They found that expensive filaments are not necessarily consistently good nor good for printing all types of projects. They found some filaments that printed extremely well until it came to laying thin support, then the entire print became wrapped around the hot end. Most frustrating was that price was not the best determinant of filament (unless it was the bargain brand)... many brands, even expensive brands showed big differences between spools, even within a spool.
At 6, 9 or even 12+ hours a print the cost of failure is just too high.