I think I see your problem. You're not using the Force Field Emitters for your shielding/armor. The "armor plates" are very heavy. The FFE is zero weight, or close. Yes, the FFE is very expensive especially if you're in early game and don't have a good supply of enderpearls yet. But just to give you an idea... I've never made a MPS where I used those iron or diamond plates for armor. FFE's are the only way to go IMO. I can fly anywhere, any direction, at any speed, and remember, my suit is maxxed out, I have EVERY accessory on it.
I appreciate the input, but I'm doubting that weight is a major factor at this point. In previous versions of the mod I'd use 5 maxed out HV batteries without any problem. I'm currently using ONE tuned to about 20%. The difference in weight there more than covers a few armor plates. Nevertheless, I will load up a creative game and give it a shot, see if it makes any difference.