thats depends on decklink bandwidth and hardware support - and their designs restrictions - and which version of hdmi spec - im not an expert
http://en.wikipedia.org/wiki/HDMI
the kona LHi seems to be claiming something like this on hdmi input:
http://www.aja.com/products/kona/konalhi/specs.php3Gb SD and HD-SDI, SMPTE-259/292/296/424
HDMI v1.3, 30/36 bits/pixel, RGB or YUV, 2.25Gbps, SD,HD, 1080p50/60
the kona 3g claims even greater input sizes
http://www.aja.com/products/kona/kona3g/specs.php