Piezos:
KSN1005A
KSN1038A
knockoff KSN1005

ok. here's the deal. this is all subjective, no measurements.

The REAL KSN1005A is at least 3 or 4 if not 5db louder than the knockoff.
The 1005A is at least 2 or 3db louder than the KSN1038A.
The KSN1038 sounds more flat than the KSN1005A.
The KSN1005A is too loud for the Alpha8.
the KSN1038A sounds very good mated with the Alpha8.
The knockoff KSN1005 has the correct level for use with the alpha8, but doesn't sound as good and not as flat (as 1038) and is missing the top octave.
The KSN1005A (since it is deeper) would have to be mounted out farther if it were used with the alpha8, physical alignment actually makes quite an audible difference.

CTS is the way to go, the extra $2 is worth it unless you are doing a 50 tweeter array in which case compression drivers would be better.

Danny