Question: We want to run the module for compatibility reasons and for better coverage primarily with proprietary, classic Nordic protocol (ShockBurst). Will the certifications (FCC, ETSI) of the radio module cover this mode as long as we remain within 10% channel utilization (without frequency hopping), or would we have to limit the percentage even more? Or do we have to recertify the module when using this option?" There were specific parameters from ShockBurst that may not be in accordance with the type of test made for BLE approvals. So we don't know if the module could comply with FCC and CE approvals for Shockburst, it might be necessary to complete actual certification test ?
Answer: This depends on what your test cases within the FCC/ETSI qualification. If FCC/ETSI certification tests were performed on 2MBIT on-air data rate (which is the worst case wrt. on-air freq. deviation), then I see no problem with running any of the other supported data rates. 10 % channel utilization should also not be any issue, unless you're transferring all the time. The amount (in %) of modulated TX carrier is heavily reduced by on-air ACKing and RX/TX ramp up (130 us for PLL settling).