I've been watching all of the SP threads on various forums with much interest. Having used SP extensively in comparison with ACR, C1, and RSE, I agree with others about the lack of shadow detail. ACR, C1, and RSE pull out more shadow detail without the penalty of low contrast in the mid and high range. Though as others have pointed out, RSE does still need a tone tweak to avoid the dreaded "gray" effect. I've found that local contrast enhancement, using the settings 20/50/0 in Photoshop's unsharp mask, to be helpful there though not a solution.
I'm an architectural photographer shooting with a Canon 1Ds and 1Ds Mark 2, and usually contrasty exteriors just aren't well handled by SP. But the color, detail, and lack of moire are A++. So I'm seeking a solution.
IMHO, SP has the best color, ACR the best tonality range, and C1 a kind of combo of the two, but not quite as good as either. And I like the tethering of C1 too.
What would satisfy me is trying to combine the color of SP with the tonality of ACR. So what I've been doing is two conversions: one is SP, one in ACR, and then pasting the ACR conversion on top of the SP in Photoshop and choosing "luminosity" for the layer mixing.
Presto, I've got the tonality of ACR with the spectacular color of SP. Alternately, you can paste the SP on top of the ACR one, and layer by choosing "color". Same result. I've created a Photoshop action that handles all of this, even fixing the 1 vertical pixel misalignment between the two converters.
Since SP offers numerous color preset options, even emulating different color films, they should also offer several default tone curves as a starting point. And I don't mean overall lower contrast, which is what the sliders and current presets give, but rather a native raw curve which preserves shadow detail without altering the midtone and highlight portion. For example, C1 has an "extra shadow" preset curve at the linear to working gamma conversion stage, and does not paste a curve on top of a curve.
I'm sure the shadow detail is there in SP, it's just that their default curve is a little steep and more like an in-camera jpeg. Just offer us more default curve options so I don't have to do my luminosity trick in ACR.
Other weaknesses are the sharpening, which isn't that great, and I get far better results in post with Photoshop. The sharpening in RSE and C1 though is excellent.
Also there is a bug that gives different shadow detail between the sRGB and aRGB option. Which is the correct shadow detail? Apparently aRGB is a textbook gamma 2.2 curve, while sRGB is defined by a slightly different curve that is not textbook 2.2 gamma, and SP is not taking this into account.
Speaking of which, SP should offer wider colorspace options, especially as the main reason people are using SP is for its incredible color accuracy and punch. They're surely not using it for its UI beauty, which is uninspired and could use a real graphic designer and some tidying up.
Would love to see a tethered option, though I know I'm just dreaming there. But, please, please, please, A NATIVE INTEL MAC VERSION! Though in Rosetta it works just OK, albeit rather slow.