I'm lowered on Koni Fully adjustables.
Pro's: Fun to thrash around - Good Handling - Adjusts to your spec
Con's: Rock solid - Damper sponge cover gets brittle (no big deal)
I recommend fitting Z3 shock mount plates to the rears while you're doing it.
If you're going stiffer, this is a must. Mine popped through the mounts 3 or 4 times, then I fitted oversize washers to try to keep them in but they just ripped straight through the wheel arch. Pissed me off!
Had to weld 1.5cm steel plates to re-mount the dampers again.
Z3 mount plates would've prevented this.
However, don't be put off from doin this, I've had suspension both ways and I'll always go lowered from now on. You won't regret it.
Read this page from Pelican parts: