They are VERY different frames, and it depends on the riding you will do. The EAI Bare Knuckle (same as the Business Cycles Nessuno) is a track frame with fairly steep angles and a relatively high bottom bracket. You can ride it on a velodrome no problem. The front fork is drilled for a brake so you can ride it on the street. The Gunnar Street Dog (as the name implies) has road bike geometry. If you are planning to ride on a track, the BK is more appropriate. If you are planning to ride significant distances on the road, the SD is probably a better choice.
yeah forgot to mention that. its going to be primarily, if not entirely, a street bike. thats another thing that drew me to the gunnar. its just so damn 'spensive. i feel like i could justify it a bit (to myself) if the bike was significantly lighter than the bare knuckles and therefore easier for my kinda pitiful twig arms to carry it up several flights of stairs. obviously my components will be on the lighter side as well. the 50cm eai i checked out today seemed comparable in weight to my 57cm vintage motobecane reynolds 531 frame (which is just under 5lbs frame alone i believe). theres a chance it was my imagination, and expectation of something lighter, but yeah, i'm definitely looking for something closer to 4lbs. is that possible? theres a very good chance i'm just a moron and i'm making numbers up too by the way. i've never owned a non-vintage bike so i'm somewhat new to this