The following effects have been proven stealable and absorbable:

Warcry, Damage Spikes, Protect, Shell, Berserk, Haste, Rhino Guard/Evasion Boost, Sand Shield/Defense Bonus, Aquaveil, Sharp Strike, Photosynthesis, All En-spells, Boost, Orcish Counterstance/Counterstance.

You can also steal any Absorb-Stat effect from a mob (That has successfully landed it on a player)

The stolen effect will overwrite your status effect if it landed it on you.

For example a DRK mob casts Absorb-DEX on you and it lands.

You can steal it's Absorb-DEX effect, and it will overwrite your -DEX effect, giving you a +DEX effect for the remaining duration.

This has not been tested on all Absorb-Stat spells, but it would stand to reason that if it works on one it will work on them all.

I find its very easy to Dispel in Ro'Maeve but as far absorb rate id put it at about 15%. This was done with a lvl 79 Thf

The following mobs have proven difficult to get an effect removed:
Skeletons/Undead (Ice Spikes), since Bone Chip is easy to steal.

Notes:

• Absorbing abilities that increase a stat will steal the percentage increase rather than the target's increase. It will also absorb the remaining duration.