Hmm.. good to know! My online search didn't turn up any specific cfw 3.15 supporting peek and poke unfortunately. I'm currently using PL3 from Danyl's Rockbox PSGroove 2.0 app.
Also didn't see any specific PL3 for 3.15 that mentions peek and poke, but i see that PSGroove patch 1.1 does (not sure how to patch). Will PSGroove Hermes v3 for 3.15 support this? There's too many versions out there.. lol. Glad we have your Backup Manager stand out to standardize upon!