By chance today I just updated one of these cameras from 5.0.9 all the way to 5.4.5. No problemas whatsoever, I can confirm everything worked fine for me.
I was also coming from 5.0.9, but my build date was 140612. To be safe, I updated ALL the firmwares one by one, without skipping any of them.
Be careful with v5.3.5 build 151209, you first need to update with digicap_eng_std.dav and then the digicap.dav inside the ZIP file.
And yes, I did update two times the versions where you have two builds (like, v5.3.5 build 151209 first, and then v5.3.5 build 160116).