Tono: I think if you first install a solder connection across U1105 pins 7 and 8, and then install FW .19 that you will still have all your Trial Options preserved, and also 10 Hz RBW. Seeing you are willing to sacrifice the other Trials for 10 Hz RBW (I would also choose this path if I were you), you don't have much to loose by doing this if I'm wrong. There was an earlier version of FW that would initially cause the loss of Trials, although they could still be recovered, but now that doesn't happen with the latter FWs. I use a Firmware Write Protect (FWP) switch on both a DSA815 (w/Boot .04) and 875 and there is no issue with installing new FW with the FWP switch always ON. My Rigol Options are all permanent, and I only use the FWP for retaining my preferred Default (vs. the factories) settings in my units.
I can send you my FWP Switch Installation Instructions if you like, but I would need a email address for you that allows the use of attachments. I previously posted them here a few times, for a week or so at a time, and then removed them along with another 80 to 100 of other postings. Ted
Edit: If you decide that you want the Instructions send me your email address via a PM. I will only use it for your info, will not share it, and I will discard it after you confirm that you have received your requested info. The attachment will be compressed with WinRAR. You can use WinRAR, UnZIP, etc to un-compress it. You can also go to
https://www.rarlab.com to download a full trial version of WinRAR to use,