I've dipper cast a lot of bullets and liked it just fine till I got a bottom pour pot. I have no interest in dipper casting since, though I would if bullet weight went over 600 700 grains. The big ones need to have the lead dumped in fast, which is where the dipper shines.
The serious negative side of dipper casting is that all the stiring mixes in dross if the pot isn't fluxed very frequently. Contrary to a commonly held notion, lead alloys do NOT seperate, so dippering doesn't keep them mixed unless one is using bearing babbit, which has what could be called floating particles of harder metal. These particles will either float or sink if not stirred regularly.
The down side of bottom pour, and I believe the only two negative points are: 1.The orfices tend to plug up gradually with crud, and 2. the buildup of crud inside the spout tends to make them drip. I cure these two problems by fastening drills into pieces of cold rolled rod, long enough so I'm working well above the melt, to keep from burning my fingers. One drill at the larger diameter where the meter rod fits, and a second which will clean the spout orfice to original diameter. To use these, remove the meter rod, twist the large drill into its hole, then the smaller, using fingers only and going gently enough that steel isn't removed. Keep an ingot mold under the spout while cleaning the spout to catch the running lead. Drop the meter rod back in and you are back to new tolerances. If you cast real large bullets, don't hesitate to open up the smaller orfice a bit. Second, I braze a piece of steel rod to the meter rod, up near the top, at right angle to the rod. When the pot starts dripping, just push down lightly and swing it from side to side to grind out any debris.
To remove junk from just the orfice, use a 1/16 diameter piece of stainless steel welding rod, bent at a right angle for about 3/4 inch. Dip it in lard or bees wax to flux it, push it up into the spout, twist and wiggle it around while raising and lowering the meter rod handle. The flux will loosen the crud quite well and let it squirt out with the first shot of lead out the spout after the wire is removed.
In case you aren't aware of the reason for the bent wire, it is so your hands aren't under the dripped and squirting lead.
I only flux the bottom pour pot occasionally. The longest time I've gone between fluxing is probably 4 months, and this with the pot running 8 to 12 hours a day about half of those 4 months, as I use the pot for checking mold diameter while cutting molds. I can pour perfectly clean bullets with a good inch of crud floating on top, because it isn't stirred up ever, even if more ingots are added.
Wheel weight metal doesn't change so far as castability or hardening qualities when heated for those hundreds of hours. Lino or other rich alloy would lose enough tin to change it some. So, if I want to cast bullets I use the same pot as for checking molds.
Hopefully this will blow a bit of mith away.