All the hybrid crops we use for food now are "GMO", it's just that their genomes were modified by generations of selective breeding and cross-pollination (trial-and-error approach) rather than methodically in a lab (the factory approach). Even organic crops are nothing like their counterparts from a few centuries ago.
It really depends on how the GMO is different, and how it is used. Example: the big risk for "BT" corn is that pests constantly exposed to the BT toxin will be selectively bred for immunity to that natural pesticide, so there are regulations requiring mixes of BT and non-BT plots intermixed with each other (so that BT-susceptible pest genes won't become extinct).