Using a breakout cable for switch to switch connection will work just fine. With the breakout cable you are not required to run all lines to the same device, or use them all at the same time. Each of the four 10GB cables will act as an individual port.  Page 406 of the configuration guide details how to split the QSFP port up into SFP+ ports. [URL]
We have ordered an M1000e chassis. We are using (2) Dell Force10 MXL blade switches for networking. My question is that the MXL switch comes with 2 QSPF+ ports. We also ordered (1) of these (SFP+ 10GbE Module, 4 port, Hot Swappable, 4x SFP+ ports (optics or direct attach cables required) (331-8187)) . WE only got 1 but we want redundancy. My question is can I use a QSFP+ breakout cable which has a 40GB connection on the MXL switch end and use 1 or 2 of the 10GB SFP+ cables on the other end into my Cisco switch? WE do not have enough 10Gbps ports at the moment to use all 4. I'm not sure if we need to use all 4 10GBps cables or can use 1 or 2 and grow into all 4? We are thinking of just returning the 331-8187 and using the breakout cable.
M1000e networking question