wouldnt matter anyway...not going to be as if you can reroll your movement speed in a game like this, your movement speed will remain constant
Do the walk, run and rolling in a similar fashion and speed to THQ's SpaceMarine and it will be just fine, For LSM, CSM that is as the very base LSM and CSM are exact equals.
Laanshor's suggestion is right on the money for me, having Loyalist/Chaos Marines have a decent run-speed but the highest stamina of any race and as such can outlast opponents if they are merely trying to straight-line dash away or are ignorant to their stamina meters and just sprint around. I think speeds should be something like 20-ish mph in a full-on sprint for Marines with Eldar clocking in at about 28 or so and Orks at around 22 or so but the stamina for each would be Marines at the top, then orks, the eldar so as to allow speed and stamina to be skill-based with tactics that may force opponents to waste their stamina coming into play. Also, I think a stamina system is a given because otherwise melee is going to be very lame, maybe not for certain races on the attack so say a Marine with a combat knife wouldn't lose stamina when attacking because it's practically weightless to him but would lose a lot of stamina when blocking whereas someone with a power-sword loses some stamina swinging but keeps a decent portion even when blocking.
From what I know which is limited space marines armor is like a second skin and doesnt inhibit there movement what so ever it is is powered which augments there abilities even more. But having space marines zip around like sonic the hedgehog wouldn't be fun. I think a good balance would be yes they move fast but if they got shot or punched they stop moving as fast sort of like in counter strike or gears of war 3 or if you get punched in the gabber you cant sprint for 5 seconds and it can stick the more you get hit.
Fix movement speed for each faction with stamina recharge is a great idea. Additional modifiers for heavy weapons (slower movement speed). However for attacks with stamina... that may be too complicated. Attacks speed should be a factor in attacks, swords faster than power fists etc. But stamina wise in combat, unless we end up fighting for long minutes.. i don't think any faction will loose stamina too fast to degrade combat effectiveness... For bikes - I'd think these should be at a constant speed. It all depends on the machine's condition and how much Promethium there is.
Something around 25-30 MPH for all the current races would probably be good, just limit how easy it is to turn while running to prevent it being spammed. But definitely no stamina bar. You can't have a stamina bar in an MMO shooter unless you want to have the forum swamped in people bitching about how it takes an hour or two to run to the nearest fight Actually, a better way to implement it would be similar to Section 8, anyone know of the overdrive system?
According to Eldar "lore" when they first encountered the Astartes, the Eldar thought they were being mocked or pranked, seeing "humanity's finest" as more awkward, slow, and clumsy than children. By this I should expect Eldar will be at least 50% faster, more accurate, and harder to be hit by than all marines - without even getting in to the psychic advantage that all Eldar should have at least in part (battle focus, anyone?!). My point is that lore is way overstated, meant to hype up fans for their fave faction. It's great as fiction, but in the games (table or online), lore can't stay true to form.