I think a lot of you are arguing past one another.
You cannot fight physics. The body underwater experiences a mixture of forces which are lifting it (positive) and forces which are sinking it (negative). If those forces are properly aligned, the body will remain in position at rest; if they are not, the body will rotate until they are. If a diver is good body position (which has a significant effect on the position in which one will come to rest) and, when motionless, notes that his feet sink, then too much lift is high on the body, or too much weight is low on it. The wetsuit diver has limited options for correcting this: They can change fins, move the tank, or move whatever lead they wear. The dry suit diver has a little more flexibility, by being able to position the air in the suit -- but it's a double-edged sword, because too much air in the feet can make the boots come off, or can seriously complicate an ascent.
Almost ANY combination of equipment can be balanced, with some effort, if enough actual lead ballast is involved. The people who get into serious issues are the ones diving warm with no exposure protection, who have nothing to move -- a set of negative fins can compel a feet-down position in that case, because one simply can't move the tank up high enough to balance them. But someone wearing the amount of neoprene you are describing ALWAYS has plenty of lead to move around. The trick is to figure out where to put it. But one must first be sure that body position isn't defeating the purpose -- a diver who is flexing at the hips and allowing the legs to drop below them that way will always end up out of trim.
The precise nature of the BC is irrelevant, and aluminum tanks can sometimes even make the job easier, by requiring more lead ballast that can be moved.
Achieving good body position AND locating weight correctly is what I believe Diver0001 is describing as good technique. Several other posters have not included the weight positioning as a component of technique, which is why I think you are arguing with one another. The best body position and finning technique in the world will not balance an unbalanced gear composition, and the best diver in the world will be unable to be motionless if the gear is sufficiently maldistributed.
BTW, here is Rob, diving in gear which was entirely new to him. The only thing he is wearing of his own is his mask:
Edited to add that he's the one in trim . . .