Brocade ICX7750: Stack Trunk Configuration For More Throughput/Redundancy

I was working with one of the local engineers in a ICX7750 stack configuration for a core install.  We were easily able to stack the two together without any issue with two stacking cables.  But, we decided we wanted all six of the 40Gig ports for stacking.  Since the default only uses two ports (1/2/1 and 1/2/4), we had to do some config work to get both port groups (3 in one port group, 3 in the other) to work.
This is how it looked when we had the two cables in place.  With a "show stack" command, here is what we saw:
ICX7750-48F Router#sh stack
T=2m48.4: alone: standalone, D: dynamic cfg, S: static
ID   Type          Role    Mac Address    Pri State   Comment
1  S ICX7750-48XGF active  609c.9f23.a380 255 local   Ready
2  S ICX7750-48XGF standby 609c.9f7f.5100 254 remote  Ready

    active       standby
     +---+        +---+
 -2/4| 1 |2/1--2/4| 2 |2/1-
 |   +---+        +---+    |
 |                                |
 |------------------------|
Standby u2 - protocols ready, can failover
Current stack management MAC is 609c.9f23.a380

#  Stack-port1                                  Stack-port2
1   up (1/2/1)                                   up (1/2/4)
2   up (2/2/1)                                   up (2/2/4)

Notice above the highlighted.  It shows a -- between connections.  This means there is one cable connecting in each port group.  Just something to notice.
Now, lets change the config for 6 ports total for stacking.
Core(config)#stack unit 1
Core(config-unit-1)#multi-stack-trunk 1/2/1 to 1/2/3 and 2/2/1 to 2/2/3
Core(config-unit-1)#
AT THIS POINT, I HAVE NOT PLUGGED IN THE CABLES INTO PORTS 1/2/4-1/2/6:
Core(config-unit-1)#multi-stack-trunk 1/2/4 to 1/2/6 and 2/2/4 to 2/2/6
Error! 1/2/4 has no connection. Please use "stack-trunk".
Core(config-unit-1)#
AFTER SEEING THE ERROR MESSAGE, I PLUG IN THE CALBES INTO THESE PORTS:
Core(config-unit-1)#multi-stack-trunk 1/2/4 to 1/2/6 and 2/2/4 to 2/2/6
Core(config-unit-1)#exit
Core(config)#exit
Core#sh stack conn
Core#
ID   Type          Role    Mac Address    Pri State   Comment
1  S ICX7750-48XGF active  609c.9f23.a380 255 local   Ready
2  S ICX7750-48XGF standby 609c.9f7f.5100 254 remote  Ready
    active       standby
     +---+        +---+
 =2/4| 1 |2/1==2/1| 2 |2/4=
 |   +---+        +---+    |
 |                                |
 |------------------------|

trunk probe results: 2 links
Link 1: u1 -- u2, num=3
  1: 1/2/1 (T0) <---> 2/2/1 (T0)
  2: 1/2/2 (T0) <---> 2/2/2 (T0)
  3: 1/2/3 (T0) <---> 2/2/3 (T0)
Link 2: u1 -- u2, num=3
  1: 1/2/4(T1) <---> 2/2/4(T1)
  2: 1/2/5(T1) <---> 2/2/5(T1)
  3: 1/2/6(T1) <---> 2/2/6(T1)
CPU to CPU packets are fine between 2 units.

Now, notice that above there are == signs instead of -- signs.  This is to show you there are multiple cables plugged into one port group.  Just something to notice.
Also, there is plenty of bandwidth between the two units and plenty of redundancy.