I am not sure how that works in etpro, but other mods set a default amount of time to temp ban a person after a kick. This is usually user-configurable. If you don't have that option in etpro, etadmin_mod provides this feature - [link=http://kmod.quakewarsterritory.com/index.php]kMod[/link] might also; it's an add-on for etpro.
What config is this? Again I am not that familiar with etpro's behavior - are you saying it autoclears that list each restart? If so, try putting the IP/GUID bans in your pbbans.dat file.
Mute him & abuse him as much as possible. Eventually it is likely he may get bored and leave. Yes, this is not really a solution, per-se, but it does tend to work. If your other players are regulars & you know them well, perhaps you can range ban for a week or so & let them know what is going on before hand & hope they'll understand.
minguidage as I understand it was a test implementation from the get go. etadmin_mod did have this feature but from what I've heard, it is buggy & guidages are not always reported.
Dedicated asshats also tend to age their guids & keep a nice stash ready to get around features such as these - so it's not as helpful as it seems at face value.
Whether they were ever of any use, I do not know. I do know, however, that they are essentially useless now. The etpro team (bani himself iirc) has stated that "etpro guids are buggy & should not be used". They are easily spoofable and it is also possible for multiple machines to get the same GUID - most famously - any Win98 install on any machine gets the same guid - & while banning all win9x users may not be a big loss percentage wise, you get the idea of the reliability of etpro guids.
These are the only GUIDs for ET that are hardware-based that I know of, unless you are referring to information used for PB Global Hardware bans, which is not available to end-users & is only done on their end.
Jaymod has added the function of MAC address banning since one of the 1.5 (what became 2.0) betas & this, though also spoofable, adds another layer of complication to cheaters' efforts to come back, increasing the odds you may bore them into leaving (and also probably foiling a percentage of cheaters who simply do not know how to bypass them)
From what I've heard the entire etpro project is abandoned. With regards to PB - what do you mean? Minguidage aside, PB is updated quite frequently for ET and it should be noted as EvenBalance have stated before, you do not always need a new 'full-blown' PB update to detect cheats - alot of that is done on their end with little to no notification (as it should be). PB Server v2.0 has just been rolled out for quite a few games & et is one of them.
apparantly i wasted my time typing the etpro guid speech above ;P
imo, EvenBalance has not shown the 'white feather'. I hate to think about what the ET scene would be like without PB. It's simply harder to manage these things in a free game then in a for-pay one w/ cd key & that, essentially, is the price you 'pay'.
ET is a great game, and we put the effort into it because we want to see it prosper & be a fun environment - you are not alone, either in your efforts or frustrations - don't give up :).