If you order from Xin (I did in 2006) you will get it now... in 2012 or 2013, maybe never. In 2006, it took 4 or 5 months, so forget about it.
The T3 is excellent. For IEM's, it has better drive than any combination of op-amps I've used in the P3+ (which I also own). The P3+ is a bit 'sweeter' sounding, but the resolution and size of the T3 is simply superb for its price. There is a little bit of hiss, but nothing devastating.
The D4 also isn't the best iem (balanced armature) amp even with the best of the best op-amp combos, but it sounds great. For portable use, I'd still take the tiny T3D over either, though it can be improved.
I have no idea when the Slim is shipping. Jason is hard at work (evidently), but pretty dark when it comes to that information. I have a feeling the Slim may just be that Duke Nukem which never came: the perfectest of portable amps. I've never seen an amp receive this much thought and revision before.