Couple of songs I made recently. Sorry for the similar intros .

For the riffs that go like 3/4,3/4,3/4,4/4 (bar 1,2,3 = 3/4 time, bar 4 = 4/4 time) keep in mind this thing I read from one of the Lamb of God guitarists:

He described this band's (Breadwinner) sound on one of their songs like a box rolling down a hill. Constantly rolling then stopping. You keep waiting for the end beat to the bar, but the next bar starts (cant remember what he actually said for that sentence, I just put it in my own words).
3. Amazing song. Everything flowed so well. not a single thing i dont like.

4. Also amazing. I like the intro in this song better. A little more simple of a song. but equally as awesome.

I can really hear the math metal here. and i love it!
I liked them. The only criticism I have to make is that perhaps it'd be good to deviate a little from the constant harmony in 3rds, try using different intervals so that it doesn't all sound the same. The outro to "4" could use the bass calming down a bit: even as a bassist I think it's a bit too busy for the bass to be following the guitars nonstop. Maybe it could follow for a bit, and then do something different (and if you're going for the complex/prog bit, it doesn't even necessarily have to be simpler, just something different from the guitars)?

Just my opinion. I did think they were well done though, I liked the time changes.