actually, no. do this math, at its purest form, kinetic energy is mass times acceleration, so its potentail energy can be measured by mass x speed. now, not wanting to look up all of the fun equations to put the numbers in newtons and bullshit like that, think about this. a 12 grain slug (22. bullet, bigger than a shaving for an ME rifle) moving at 12,000 feet per second can deliver a maximun "force" of 144,000 (again, not the scientific measurment system, simply the same concept. the math is the same, the measurments are not) good amount of potential force right? now, a 7.62 is generally a 150 grain slug, and lets put that at 2500 feet per second. that is slower than a 5.56 round from an M4 carbine. that would have the potiential force of 375,000. if i were to do this in meters per second and all of the fun scientific number crunching, you would have the same result. a 7.62 traveling much slower, still has more kinetic energy than a needle traveling really fast. so, more than likely, it woulld be as effecive if not more effective than a round fired from a mass effect weapon. and, more than likely, they have way better powder and chambers than we have now, allowing for higher muzzle velocities (that is actually a low muzzle velocitiy for a modern rifle) so, if a burst of those weak 'needle' shots can take down a kenitic barrier, a burst from an MA seires weapon can too. and if a spartan can smash a brutes face in with his fist, he can smash a krogans. brutes faces laugh at AP 7.62 rounds, an 9.6 from the battle rifle manages to barely punch trhough. so if a hyper fast needle can punch through, so can a heavy slow slug. yeah, the needle will reach the target first, but it will not have the ability to punch through as well as a modern round. the advantage of a ME weapon is the fact that you dont have to carry ammunition, which can be bulky and cumbersome. they directly say in Mass Effect that their armor is a ceramic plates and a fiber armor underlay. the underlay, to do the very weaving process or whatever process is used to make it malluble, would make it very weak. Marine armor is a multi layerwd system, designed to slow and stop the round, the outer most layer being a metal alloy, much like modern IOTV's the US armor uses, coupleing modern ceramic armor and kevelar to reduce impact. and yes, there are weak spots wherever there is no plats but thats the same with Mass Effect armor. so yes, their rounds are fast, but not actually all that powerful. (Get the real numbers for a mass effect round, an i bet you, a 7.62 still hits with more force.) and the cheifs sheild can take SEVERAL bursts from an MA5 with out dropping. more force, more rounds, and oh, it stops more than projectiles. want proof that the bigger rounds do more damage, even when slower? look up armor torture tests. also, go watch the video game theroy on spartan armor, where an armor EXPERT, mentions exactly what i just said.
and yes, ODST's are comparable to N7, becaus the N7 are basically the navy seals, green berets, and SAS of Mass effect. guess what, ODST's, fill the same niche. and yes, elite shielding is better than Mijolner sheilding, but we aren't comparing elites to spartans, now are we? and yes, Mako's are light vehicles, but, their are not ANY heavy vehicles in Mass Effect, because their ships lack the capability to haul and deploy them. and Seren and Kai leng are the absolute top of the line barriers, so using them to compare to spartan energy sheilding is simply stupid. oh, and again, they can not stop thermal based weapons fire, I.E., plasma, a thermite grenade, flamethrower, HEAT rounds. all of those would easily knock out kinetic barriers, by the lore. also, UNSC air power (Long swords, hornets, pelicans) could easily paste their ground forces with high yeild explosives (I dont give a crap how awesome your little infantry shield is, it wont stand up to half a dozen 2000 lb JDAM's being dropped on you, or a 440mm artillery shell)
and yet, although the UNSC was nearly wipped from the galaxy, which side took the numerically greater losses? even before the great schism? two thousand on three hundred, three hundred die, but kill a thousand, yeah you one, but which side was actually the better fighters?