I like Bego (a little tougher),there tends to be less reaction layer vs. microstar.. microstar is easier to de-vest.. they both have +/-
as for the number of units? fit them in.. 4 posteriors/ 5 anteriors is definitely do-able. if your concerned about the weight, weigh them with the sprues and press at 80-85g. if you are pushing the weight (90-95),drop in an already fired ingot (make sure it fits first) behind the old one.. (just to be sure your new ingot doesn't run dry)
keep a timer on all stages and be religiously consistent (you can't make adjustments if there isn't consistency)
last place I was at, we ran 30 units a day (pressing) and rarely, rarely had a miss press caused by crowding