It's yet another module format, but MEN Micro had a reason for introducing its new Universal Submodule (see the Figure) architecture. The Universal Submodule (USM) is designed to sit between the outside world and any base board that will typically have an FPGA on it. The base boards can be any thing from a PMC to an XMC. This allows easier user customization, and also allows the same interface to be used with different base boards.
MEN Micro is creating a number of standard base boards for different form factors. It will also have ISM boards, but these will likely be customized for most customers.
Pricing for the complete development package with either an M-Module or PMC base board is $2,654. For more information, visit MEN Micro.