Ok, I've tried the following Cases:
D3O Dual Impact
Body Glove Revel
Reiko (posted a review here)
Trident Aegis for the GSII/Epic 4G/SPH-D710 (wrong model but close enough that the case fit, for the most part)
The hybrid case with the mesh hard plastic
And now the Trident Aegis for the T989
I gotta go with the Trident Aegis for the T989 hands down.
D3O Dual Impact: Good case, good fit, good protecion, did not like how stiff the buttons are.
Body Glove Revel: Second favorite case. only reason I'm not using it i cuz I gave it to my wife.
Reiko: Good case, really good protection. Liked the kickstand. But it made the phone HUGE.
The hybrid case with the mesh hard plastic: Eh... ok case, fit well but silicon cove was somewhat loose, the mesh plastic feels flimsy. Micro USB cutout is small.
Trident Aegis for the GSII/Epic 4G/SPH-D710: Wrong model but it fits for the most part. The camera lens cutout is off but doesn't obstruct the lens at all. The 3.5mm jack cutout is a little off but doesn't prevent the jack from being used. All other cutouts matched up. The fit was tight. I "liked" that the hard plastic shell covered the bottom as opposed to the T989 Aegis which doesn't. BUT, I dropped it once and the plastic shell covering the bottom cracked at the micro usb cutout.
Trident Aegis for the T989: Fits like a GLOVE. Nice and tight. Good lip around the screen. Not concerned at ALL anymore about the hard plastic not covering the bottom. In fact after my experience with the D710 case I LIKE that it doesn't cover the bottom. The silicone cover is thicker at the bottom. All 4 corners are nice and thick. Fees good in the hand. Easy in and out of pockets. Dust covers over the 3.5mm jack and micro usb are tight. Every case adds some bulk to a phone. I think this one feels nice. Found it on Amazon for under $20 w/free shipping.
My 2 cents