Just to reassure:
What I now see in Thomas license code, that the entries for 1 Hz and 3 Mhz RBW which were working in 7.07 are gone. In 7.07 there was <_1HZ>TRUE</_1HZ><_3M>TRUE</_3M>
I read in this thread, that 1 Hz and 3 Mhz RBW are not available anymore starting from FW 8.1 so I just should delete this now before updating? Would it hurt to keep it?
From FW 8.5 the 1 Hz will be back anyway, am I correct?
Yes. Siglent activated 3 and 1Hz 8.5. But not 3MHz
Of course after you have made this all right way and system have generated all official license keys you can after then use also other (possible in FW 8.x) modification what do not care anything your model and option licenses and you get same 3.2GHz and all options functional + 3MHz unspecified experimental grade RBW available
So, if you make it right way you can then when ever turn it back to "official" mode and you have there official options license keys and official 3.2GHz model license, only what is different to official is front panel label.
But also now in this case, you do not have 2.1GHz version license. If you want (some reason, example sending it to Siglent service) turn it to official mode, matching also with front panel label 3021X you can not - due to lack of 3021X model license! (so think what license/product key you want - you can get only one.)
At this point when you still are with FW7.7 you can carefully think what license you want and is wise but also it need think that some day Siglent may change system and mods dop not work. If you have official 3032X license there... you know future FW also keep it as 3032X. If you have there 3021X license future FW sure keep it as 3021X and here you can run it with super mode mod and it works like 3032X as long as Siglent do not destroy this (and markets) in some future FW.
You can now in 7.7 select which one you want and is more wise for you. Later in FW 8.x (least with FW8.5a what is most new at this time) you can modify it so that it do not care these licenses at all and it works like 3.2G and all options on and including also experimental RBW 3MHz. But as told this "feature" Siglent can stop in some future FW if they want. But if you have all official licenses for all options and product key for 3032X it stay. Only situation when these are generated is process what is running once when system is updating from 7.x to 8.1.