I have had the exact opposite experience. My cubans are more than happy to sink their little "teeth" into any cichlid big or small. My cubans had no trouble sharing a tank with a larger pair of midas and did some damage to the female when they got in fights. My male cuban is a tyrant and can only be housed with larger tankmates. They are defiantly all bite.They tend to be slower growers and can hold their own in a community tank, but I haven't kept them with any super aggressive centrals. I have a pair in a 180gal with some other centrals and so far they haven't caused many problems. A lot more bark than bite so far. Sexing can be near impossible until they pair up, unless you are able to vent. I had a group originally and a few I pegged out for females turned out to be male.
Pics of my pair from 6 months ago... when they were by themselves in a 55gal (Male was 4.5" and female was only 4" back then)
I wish I had your luck! These guys seem like they are getting close but nothing ever results.I believe I have one of the largest males on MFK...
I have to go to lengths to get them not to breed more often. I can't get rid of the fry locally!