My current understanding of the the LimeSDR USB and LimeSDR PCIe is that if one can do what you want then the other one probably can as well. But there might be a little bit more room in the FPGA on the USB over the PCIe for two reasons:
- The PCIe FPGA is smaller EP4CGX 30 CF23C7N (PCIe) vs EP4CE 40 F23C8N (USB 3.0)
- Additional gateware needs to be loaded on the FPGA to drive the PCIe so there would be less free room on the FPGA.
I have no idea about the latency, but I would guess that the PCIe latency would be lower.