It surprises me to see how many ML shooters are apparently more concerned with their convenience while loading than they are with the accuracy of their shooting. Sure, if you use a loose enough patch/ball combination it's easier to load. It's also less accurate, in my experience. The more "play" there is between the bullet and the bore, the more random gas release when firing and the more variation in shot placement at any range. Handloaders of modern ammo preach the removal (or avoidance) of as much variation as possible, to achieve consistency and establish as much control as possible. Guess what, boys and girls, muzzleloaders hand-load every shot and if we want the best accuracy we should try to eliminate as much variation as possible.
There's also a legitimate safety concern. It's been my observation and experience that loose fitting patch/ball combos have a nasty tendency to drift towards the muzzle during a hunt, especially in a smooth bore and especially if you carry your gun with the muzzle angled down.
And while I'm up on this stump, here's another two cents worth: If you load round ball with the sprue up, you can tell where that sprue is. If you load with the sprue down you really don't know if it's in line with the bore like you hope it is or off-center. If it's off-center, that will affect the flight of the ball and reduce your accuracy.
Of course, if you choose to load loose patch/ball combinations or load round ball with the sprue out of sight (or both!) you would be welcome to pay your entry fees and shoot in competition with most of the ML shooters I've ever met.