In case anyone is wondering (like I was), the BlueDuino can scan and receive advertisements from beacons using iBeacon, AltBeacon, and EddystoneUID formats.
In my very rough first testing, the scan results are inconsistent for beacons using the Eddystone format, i.e. sometimes fast but sometimes very slow scans (I have no idea why).
The results for beacons running iBeacon and AltBeacon format seem about the same, but I am modifying a sketch now to calculate the actual results to compare the two in more detail.