After reviewing the various Cisco docs in more detail, I noted some inconsistencies between two different 9100 series hardware install guides (online vs PDF), so I opened a case with Cisco to confirm the behavior of the devices once the cables have been implemented.
This appears to be a case of poorly-written documentation. The switches do not "stack" to create a single logical switch. When connected, the switches will form an ISL** and retain separate domain ID's, which is the behavior I've verified by reviewing the showtech details for two switches connected this way.
EXAMPLE OUTPUT:
SW1
fc1/33 1 auto on trunking c1470 TE 10 --
fc1/34 1 auto on trunking c1470 TE 10 --
SW2
fc1/33 1 auto on trunking c1470 TE 10 --
fc1/34 1 auto on trunking c1470 TE 10 --
**The 'Cisco MDS 9100 Series Hardware Installation Guide' (OL-21514-01) states:
A 64-port switch can be formed out of Cisco two MDS 9134 Switches by using a copper CX4 X2 transceiver as an Inter-Switch Link (ISL).