M-Audio's history of driver support, or the lack thereof, would make me very reluctant to buy any of their MIDI products. Waiting years for a driver update is something that puts me off a product.
As does the amazing ability of a MIDISport 2x2 Anniversary to garble sysex and NRPNs. I have one and it's scrambled the patches on my Mopho under WinXP, Vista, 7 and 8.1. Also OS X Yosemite and El Cap, despite it being claimed to be "class compliant". If forums are anything to go by I'm not alone in that experience.
It seems OK for everyday 7-bit MIDI other than sysex, but I wouldn't recommend M-Audio MIDI interfaces.
I've been using MOTU for a few years now, and their MIDI interfaces seem very solid. At least, I've had no problems.
Edited to add -
MIDI interfaces don't affect what we generally mean by DAW latency, that latency is a product of the audio driver/interface and how long it takes the software and operatimg system to process the audio side of things.
There's always a tiny bit of latency in MIDI because it's a serial protocol so daisy-chains see a progressively delayed signal and because different synths take different amounts of time to process incoming MIDI and output a sound. Even MIDI-controlled analogue gear has this limitation. Generally it's very, very few milliseconds indeed, and if it's consistent across all devices (unlikely) or you only use one hardware synth Sonar has a setting in preferences where you can apply an offset to Sonar automatically compensates.
I've several synths so generally have to slightly shift audio clips to get them to align with the relevant MIDI track. Unless the slight difference doesn't make any audible difference when I leave it alone.