The biggest issue I seem to have with integrated belts is there is more space, in the bcd I used, in the front than back.
And, this has been an issue with a number of weight-integrated BCDs, and has given back-inflation BCDs a bad (and undeserved) reputation in the past, for pulling divers face-forward at the surface. Newer divers would use a weight-integrated system, where the weight position was forward of the diver's midline, while the center of lift was aft of that midline. The diver was probably a bit overweighted (as more than a few newer divers are), they would use their BCD to overcome the weight issue, which placed lift above and behind the weight and over they would go. And, it was made more acute when the diver was using an AL cylinder, instead of a heavier /more negative, steel cylinder.
I first practiced 2 years ago with weight belts and I didn't mind them. I found integrated systems more comfortable though, and the biggest problem with the belt system was the fact that it would slowly sag throughout the dive and be really loose by the end, increasing discomfort.
And, if you are wearing thick neoprene, which compresses as you descend, you might find that a belt that was snug on the surface is now loose under the water. There is nothing wrong with tightening the belt at depth. In fact, it is a good idea.
However I like the fact that I can arrange the weights around my hip any way I see fit.
And, that is something of an advantage, although the center of weight, on the plane of your body from head to foot, is still the same.
Four additional thoughts in response to your original question:
1. I have used both an integrated weight system (on my Zeagle Ranger) and a weight belt (for most of my diving), and personally prefer the belt. (I actually prefer a rubber weight belt over a web belt, but that is another topic.). I have enough hip that I can use a belt, cinch it tight and it stays on. I do recognize, however, that there are a number of people for whom that is not the case, and the potential for a weight belt to slip off underwater, leading to an uncontrolled buoyant ascent, is not to be taken lightly. So, while I may prefer a belt, I do not believe a belt is best for everyone.
2. One (of many) reason(s) that I use, and prefer, a steel backplate is that it moves weight 'up' toward my shoulders, Many / most jacket and back-inflate BCDs are postively buoyant. Placing weight on the diver's waist (or toward the lower part of the BCD) to compensate for the buoyancy characteristics of the BCD, creates a mal-distribution of lift and weight. A steel backplate helps to offset this, and is a useful consideration for divers that need added weight, based on their exposure suit, body compositioon, and diving environment (salt water, cold water, etc.).
3. The scuba equipment world appears to be moving inexorably to a predominantly weight-integrated BCD existence. I was discussing this with our shop owner yesterday, and had not until then fully appreciated how significant the shift has become, in terms of what kinds of BCDs are available in various manufacturer lines. And, although you don't have to use weight integration with a weight-integrated BCD, the design and 'cut' (longer in the torso) of some weight-integrated BCDs makes use of a weight belt difficult. The good news is that the sophistication of weight placement in integrated systems is improving, and some of the problems you experienced (e.g. feeling of being pulled forward) are being addressed by the distribution of weight placement in some newer systems. Simply putting all of the weight in pockets toward the lower front of the BCD has not been a good idea, and more manufactureres are adding trim pockets for weight placement to address this. Not all of that weight is necessarily ditchable, though.
4. I think that achieving ideal weight distribution may preclude the sole use of either a weight belt or a weight-integrated BCD for some divers. As Instructors, we work to help our OW (and beyond) students come to understand the value of good horizontal trim, and are at times perhaps a bit critical of divers who swim in a 45 degree angle, head up, position. But, part of that in-water posture may reflect the effects of putting A LOT of weight on a belt, which may bring the diver's hips and legs down. This past weekend, I had several female OW student divers, wearing jacket BCDs, using very thick neoprene because of the water temps (and consequently needing a bit of lead), and in each case found that despite their best efforts to hold horizontal trim, the weight around their waist was pulling their legs down. In several cases I took weight off their waist and moved it to the tank valve area (ankle weights are useful for this) and trim noticeably improved.
I have the back weights set on the upper tank band which leaves me perfectly balanced and horizontal.
I said it with a smile, let's keep it friendly in here).
