Yes, the MRF-350 is very different from an MRF-300. The MRF-300 can be used with an RFX-250 or an RFX-150. The MRF-350 is optimized for the RFX-250 and will not work well with the RFX-150 at all.

To further clarify, here is how we order the level of RF performance:

Best - RFX-250 with MRF-350
2nd Best - RFX-250 with MRF-300
3rd- RFX-150 with MRF-300
4th- MRF-250

Never connect an RFX-150 AND an RFX-250.

Best Regards,

-Eric