Okay, we all know why weight classes exist in fighting sports, they're due to the clear advantage of the heavier opponent.

what my question is, what are your guys-es opinion on this situation.

opponent 1 5'5" 170, opponent 2 6'0" 170 lbs.

lets just say these guys are both mixed martial artists, and somewhat proficient in their own way.

Do you think the height difference will effect the outcome of the fight?

or should i say, do you think that height is a deciding factor in a fight?

Reach would be more of an issue than height IMO.
Jake

Short guys are usually better looking.

um..uh..actually... short GIRLS are usually better looking...

i think height is considered to choose technique.it's factor but not important factor

The small guy will probably be used to taller training partners, and the tall guy will be used to shorter partners, so they're both going to be ready for each other anyway.

im assuming that all of us are short, right? lol

I wonder if there is a reason why you dont see shorter light heavyweights or any short people for that matter in major fight venues like ufc or pride.

I am 5'5 and 170ish... and I have to say that it depends only on your style of fighting(mind set). If you want to grapple, then the bigger guy will win. If you stay away and dodge his punches etc. and strike his throws(muscle jabs) then the shorter guy will win.

I have seen a few short people in local full contact like UFC and one dude about 4'10 (thai boxer) absolutely messed people up, the guy was very fast and skilled.

I think there are pros and cons to both.

when it comes to striking reach is always important and usually the taller guy has the better reach but it also seems that the shorter guy can pack on a little more muscle than the taller guy of the same weight making him a little stronger.
Mike Tyson was pretty short for a heavyweight but he seemed to do pretty good, then again he also lost to Buster Douglas who had something like a thirteen-inch reach advantage over Mike.

When it comes to grappling I've always thought that taller guys could get certain techniques easier such as the triangle because their legs are longer but shorter guys I think would be able to escape certain moves easier like replacing the guard from under someones mount. I also think shorter guys are able to do some throws better than taller guys. such as a simple hip toss since they'll be able to get under their opponents hips easier.

just my opinions I could be way off I'm no instructor.

I've had my butt kicked pretty-good by folks both shorter & taller than myself... skills weren't equally matched in any of these cases (I suck at wrestling & don't kick too well & I've been kicked-around by a somewhat proficient kick-boxing/Tae-Kwon-Do practitioner & tied-up &/or choked several times by somewhat proficient grapplers).

Like others have said, height is a factor but not a deciding factor.

Randy Couture vs Tim Sylvia as an actual example of this situation in MMA