I have submitted both vectors and jpegs.  They accepted all 19 of my images in jpeg format only.  After one month and one inquiry to their help desk, I have yet to hear whether they have accepted or rejected these same images as vectors. 

Hilarious.  Now if only they could put that much time and energy into approving or rejecting the vectors I submitted to them last month.

Thanks everyone!  I'll keep my eye on the Best Matches.

This is what I saw recently on the iStock forums as a response to the question why are my sales slow.  I asked in their forum what may be the reason the vector images I have on iStock are not selling.  I started selling there 5 weeks ago. The same images are on Shutterstock and I've made 250% more money in half the time.  I've asked for an explanation for this 3 month time period, but so far no one has replied.  Can anybody share  their insights?