Calidris sp, minuta or pusilla?

Calidris sp 

This hard-to-identify Calidris species was found at the Salinas in Fuencaliente by a visiting birder a few days ago. I spent the best part of this morning attempting to photograph the bird's feet, trying to see some evidence of webbing and thereby clinch the id. However, there was a strong wind blowing, and several other jittery waders foraging nearby, making close approach difficult. So, the pictures shown here don't clarify things completely.

The doubt, of course, is between Little Stint (Calidris minuta) or a vagrant Semi-palmated Sandpiper (C. pusilla). 

For a juvenile Little Stint, the plumage is very pale: there are virtually no traces of rufous tones whatsoever, and the bird lacks a conspicuous double supercillium. But something like a thin, scapular "V" can be appreciated in the photo below. The bill is rather long for pusilla, in my opinion (although longer-billed specimens do apparently occur), and not straight enough. Also, the primary projection looks a bit long for pusilla.

I heard the bird call briefly on one occasion, and it sounded like a short series of high-pitched, staccato stits. As previously mentioned, it was very windy, and there were other waders around, so I can't be 100% certain.

Little Stint (Calidris minuta) or Semi-palmated Sandpiper (C. pusilla)?

On the basis of plumage and bill details, a number of experienced birders have suggested pusilla to me.  I am tending towards minuta, but am not entirely convinced, pending a decent picture of the bird's feet.

Any comments would be appreciated.