In my cube's core, there are eleven 2/1s and five 2/3s that Sea Gate would be better against, but only seven-ish are aggro cards. On the other hand, there are 48 X/2s, of which at least ~33 are better blocked by Cloudkin. I think that settles it
There's also that 2/1 für 2U from the new tarkir set that has the same ability as SGO but with putting the 2nd card into the yard if you have gy synergies.