Yes it is true that the switches can work together.
but there is a difference in working together and working together.
If fx you take the 3750x switches.
the three of them in a stack with none of the others will give you 64 gig stackwise+, you can do a stack that is redundant with powersupplies and powerstacking and with that you can tell the switches that IF there for any reason should be a power shortage shut down these ports then this switch and so on so you protect the most valuable assets.
the switches all can do local switching so when you need to send something over the data stack there is more than likely ample space for it.
all of the stacked switches share the exact same code and microcode.
this is a stack that works together.
Now we add the 3750E
well we still have the 64gb stackwise+ and we still have local switching but they can not make use of the powerstack, the good news is that the software is still the same so this is still a stack that works together.
Now we add the 3750G and the 3750 switch
This is where things change.
The stack now is no longer compatible with stackwise+ and have to change down to stackwise.
we are now down to 32gig instead of 64.
The 3750G and the 3750 can not do local switching wich means that every packet that enters their port needs to be sent out on the stackwise.
so first we lost half the speed then we add alot of traffic to the stackwise.
now to the code, its the same version but it is not the same code. so there will be differences in how they process things. the microcode is most likely not the same at all.
This is a stack that "works".
But you have lost both features, speed and most likely stability.
Everytime you go to an older version ov the switches you loose something.
so I would start with breaking apart the stack and do etherchannel between the 2 stacks.
if that is not possible then I would start with getting rid of the universal image and go with the ip-services image for the 3750X and E.
does this mean that the 3750 and 3750G are bad switches ?
no it just means that newer switch are better.
Good luck
HTH
