*5.1 While we do not require the use of hardware protection, we RECOMMEND that the security of the OCSP responder key be in parity with the CA issuing key.
[This is a meaningless recommendation, because we have no single standard for CA issuing keys. Also, there are differences in the way OCSP and CA issuers are handled - you can change the OCSP key pair every hour if you want. Disagree about HSM.
Reading the text again, I realize that I had Authorized responders in mind. What the text says is that there should some correlation between how securely you operate your CA, and how securely you provide current status of those certificates. This comment should be expanded and moved elsewhere. I have no problems adding your suggested text:
Access to OCSP responder keys must be carefully controlled. In all cases system level access to OCSP responder systems must be limited and logged. Access to key backup media must also be limited and logged. For OCSP responders using software crypto stores, we recommend that this key NOT be backed up. We also recommend the key be changed more frequently than end user signing keys. These steps can reduce but not eliminate the demand for hardware crypto stores; hardware security modules should be used for high visibilty OCSP responders (see also prev paragraph?). Service providers should also consider transponder configurations to reduce the number of highly secured OCSP responder keys needed.