If Spiller keeps this up, jackson will be no more than in a time share I believe, which is no good for anyone in fantasy.
As far as the trade...I am hesitant with overstating how much better megatron is than everyone else. He is by far the best, but I think your drop to vincent jax is far lower a drop than going from R.Bush (who I think is going to keep it goin this year) to any detroit back.
I would hold off.
10-team keeper league - QB, 2 RB, 2 WR, TE, FLEX, D/ST, K
QB - Newton, Palmer
RB - R. Matthews, Martin, Stewart, F. Jones, B. Brown
WR - Julio, Austin, Maclin, Heyward-Bey, Amendola, D. Alexander
TE - Graham
D/ST - Bears
K - Tynes