i can see you having to make a bit more better engines to get the big critters more efficiently since you will have to cull them away in order to score with them
For sure, and you find yourself making purchases based on what can get you the most bang-for-your-buck glory wise. And sometimes you might purchase other dice with little plans of ever scoring them and instead keep them around for good defense/attack purposes (for instance, the warrior of the quay who grants +1 att./def. to other creatures but is worth only 2 glory).
I should note that we also played with the extra buy variant which I tend to like much better as well.