Never having used a K3T or variant, I can only speak generally.
Most grinders will get a build up of grinds somewhere, various methods of managing this depending on the grinder, easiest might be to leave them till next use, and catch the first few grams of grinds in a spare container. Im sure there would be some comments by other users in the "Grinders" section.
As far as timed dosing is concerned, IF you have same beans all the time and they are within 2weeks of roasting, and you have reasonably constant temperature and humidity in the room where the machines live, then the timed grind should be reasonably OK most of the time,...
most of us would find that limited daily use, and varying bean types mean we are better to grind manually most of the time.
However if you are catering to a large group, then you might find that the timed grind is quite handy ;)