Seems like it has higher access times...
But I don't find these speeds to be low in any way, with 4 ACards at SATA150, you would max out at ~450-480 MB/s for all 4.
The ridicolously high reads/writes (>1GB/s) are just cached reads/writes, so they're not comparable.

As for the 12 ACard not doing >1GB/s, that's another thing.. try setting volume read ahead to aggressive? It could be the 1880 just doesn't like SATA well.