I have the Valkyrie. The most important difference between it and the ECO is the barrel length -- 4.25 inches for the Valkyrie and 3.5 inches for the ECO. For serious defensive purposes, the 4.25 inch barrel (Commander length) is inherently more reliable. That doesn't mean a 1911 with a shorter barrel is unreliable; it's just more difficult to make as reliable as one with a longer barrel.
Accuracy --- There should be no inherent difference because both will stabilize the bullets just fine. However, the longer barrel will be a bit more practically accurate for most people because it has a longer sight radius.
Recoil --- The felt recoil will be a bit more in the ECO because it has less mass. However, it shouldn't be a great deal different (see muzzle flip below). Also, IMO, standard pressure .45 acp premium hollow points perform well from 4.25 inch barrels but not as well from 3.5 inch barrels. Going to +P in the ECO will increase recoil noticeably.
Muzzle Flip -- Muzzle flip will be more noticeable with the ECO because of the shorter barrel using similar loads.
Concealability -- For IWB concealed carry, the Valkyrie will conceal just as well as the ECO because it is the length of the grip frame that matters, rather than the length of the barrel.
If you want a full length guide rod (not necessary), they're cheap and easy to install. I don't see the attraction of a bull barrel just to have a bull barrel. Nothing really against them, though.