Not to rain on your creativity, high-avatar, but I'd have to agree with the others who have posted here. The problem with your hormagaunt idea is that they are more expensive than a space marine, but will not stand up to either shooting or cc like one. Combine that with the 'shoot the big ones' rule and realize that you can't even screen them with cheaper gaunts. They may work against an opponent who does not know how effective they are, but once your opponents learn about them they will die quickly.
Combine that with the fact that for the same number of points, you can get 16 'normal' hormagaunts. 48 str 3 attacks, vs 40 str 4 attacks on the charge. Against a SM tac squad your looking at 8 successful wounds for the normal gaunts vs 10 wounds for your dracogaunts.
Now consider that 10 marines with bolters will likely get 1 turn of shooting in and normally kill about 4 gaunts. Then your looking at 36 normal attacks vs 24 dracogaunt attacks. That comes to 6 wounds inflicted each on the charge.