Here are some simulations for heads-up situations.
http://twodimes.net/h/?z=1432179
pokenum -mc 500000 -o8 qs kc kh qd - ad 5s 2h 8s
Omaha Hi/Low 8-or-better: 500000 sampled boards
cards scoop HIwin HIlos HItie LOwin LOlos LOtie EV
Qs Kc Qd Kh 155684 285912 214088 0 0 0 0 0.442
8s 5s Ad 2h 214088 214088 285912 0 310438 0 0 0.558
http://twodimes.net/h/?z=1432186
pokenum -mc 500000 -o8 as kc th qd - ad 5s 2h 3c
Omaha Hi/Low 8-or-better: 500000 sampled boards
cards scoop HIwin HIlos HItie LOwin LOlos LOtie EV
As Kc Qd Th 182259 310057 189943 0 0 0 0 0.492
5s 3c Ad 2h 189943 189943 310057 0 291833 0 0 0.508
http://twodimes.net/h/?z=1432193
pokenum -mc 500000 -o8 as kc kh qd - 4d 5s 7h 6c
Omaha Hi/Low 8-or-better: 500000 sampled boards
cards scoop HIwin HIlos HItie LOwin LOlos LOtie EV
As Kc Qd Kh 169747 281410 218590 0 0 0 0 0.451
5s 6c 4d 7h 218590 218590 281410 0 291017 0 0 0.549
http://twodimes.net/h/?z=1432196
pokenum -mc 500000 -o8 qs kc kh qd - 2d 3s 4h ac
Omaha Hi/Low 8-or-better: 500000 sampled boards
cards scoop HIwin HIlos HItie LOwin LOlos LOtie EV
Qs Kc Qd Kh 165910 307438 192562 0 0 0 0 0.473
3s Ac 2d 4h 192562 192562 307438 0 310732 0 0 0.527
http://twodimes.net/h/?z=1432199
pokenum -mc 500000 -o8 as kc kh qd - 2d 3s 4h 5c
Omaha Hi/Low 8-or-better: 500000 sampled boards
cards scoop HIwin HIlos HItie LOwin LOlos LOtie EV
As Kc Qd Kh 180744 306864 193136 0 0 0 0 0.488
3s 5c 2d 4h 193136 193136 306864 0 291439 0 0 0.512
http://twodimes.net/h/?z=1432201
pokenum -mc 500000 -o8 as kc kh qd - ad 2s 4h 8c
Omaha Hi/Low 8-or-better: 500000 sampled boards
cards scoop HIwin HIlos HItie LOwin LOlos LOtie EV
As Kc Qd Kh 188814 340707 159293 0 0 0 0 0.530
2s 8c Ad 4h 159293 159293 340707 0 291884 0 0 0.470
http://twodimes.net/h/?z=1432206
pokenum -mc 500000 -o8 as ac kh qd - ad 2s 4h 8c
Omaha Hi/Low 8-or-better: 500000 sampled boards
cards scoop HIwin HIlos HItie LOwin LOlos LOtie EV
As Ac Qd Kh 204959 353364 146636 0 0 0 0 0.558
2s 8c Ad 4h 146636 146636 353364 0 271767 0 0 0.442
Some observations:
A low mixed bag vs. a high mixed bag is usually a coinflip or the low bag is a favourite.
A high hand without an ace is usually a dog against a low hand with an ace.
In general, the high hand seems to do worse than the low hand.
One time when the high hand is a favourite, is when the high hand has an ace and a pair, e.g. AQQJ vs. a low hand with an ace. However, if the low hand doesn't have an ace, it's usually a coinflip or the low hand is a favourite.
AAxx hands are always a favourite, unless they're up against a better AA hand.