It turns out that it is the only "Thunderbolt Aware" SDHC card reader/writer around right now. Just wondering if anyone is using it successfully to record on to SDHC cards on the F3 or EX1/3.

Sonnet - SDXC UHS-I Pro Reader/Writer ExpressCard/34 (http://www.sonnettech.com/product/sdxcproreader.html)

I've got the new Sonnet Thunderbolt Expresscard 34 adapter ( Sonnet - Echo ExpressCard/34 Thunderbolt Adapter (http://www.sonnettech.com/product/echoexpresscard34thunderbolt.html) ) working with my MBP Retina now, and so far only the Sonnet Expresscard 34 devices work, click on the Compatible Devices" tab (second link) to see them.

So far, my Sonnet SATA Expresscard and FW800 Expresscard have thunderbolt aware drivers and once downloaded they both are working. Would be nice though to have a super high speed transfer option for recorded SDHC cards in the field provided of course that they work in the cameras.

The EchoExpress works great with SxS cards. Very fast transfers. I'm not sure that the SDXC adapter will work. SxS cards are not quite standard PCI-E when it comes to handshaking and data transfer (hence the need for dedicated SxS drivers). Sony's XQD cards and adapter work in the F3 and these will give transfer speeds not that much slower than SxS, 125MB/s. In addition you can use a $60 USB 3 adapter to read the cards. Trouble is the cards are still quite expensive, about $200 for a 16Gb card.

In truth, only USB interface based Expresscards (with the exception of XQD cards) are allowed as media adapters for the XDCAM EX lineup.

I believe the official Sony SDHC supports UHS 1 speeds, (tested on some Sandisk UHS 1 cards and it formats twice as fast as my Kingston) but I'm not certain on SDXC. I would like to know if SDXC offers the extended capacity on the Sony SDHC adapter.

I'll just get one of these Sonnet reader/writers and use it for TBolt transfers, and continue using older MxR and Hoodman adapters to record via SDHC cards in camera. I've gotten many clients to just buy the Class 10 SDHC cards so that they can walk away with the camera original (mostly EX shoots) and not wait for transfers. Not all though..

Will report transfer speed results after tested.