I don't have anything against the MCCANNS neither i do have any clue about what happened to Madeleine but my way of thinking is a bitter different then the way of thinking of the majority of people.
When i'm dealing with a missing children case (and i'm starting to review another cold case not Madeleine related) i do care for the missing girl in the first place so for me the worst case is always prolonged pain.
I did read several stuff about the Madeleine case over the years and I do live in Portugal so I was "forced" by the media to know the case as on the time all that people talked about was Madeleine case and when that "idea" of Madeleine dying in the appartment from over-dose of medicine came along even if strong PRO-MCCANN people would consider that horrible I can tell you that if it were a child that i were to care for i would rather have her dying from an over-dose of medicine without pain and in her bed rather than something like Alesha MacPhail case or even worse (keeping the child for days in pain).
Assuming that CB would actualy go to the "extreme" of capturing a little girl and "use it for days" as expressed on the media and assuming that "using" is related to torture/rape then yes, i want him to be 100% "clean" without margin of doubth from all of that because if police can reach the conclusion that he didn't commit that sort of crime then it will mean that the victims/children/little girls that he his investigated over for possible link to the crime might still have died of other causes.
If CB is found to be guilty then it's over. If police can search CB as extensively as possible and if police can't find nothing that links him to that sort of crimes then I will sleep better,
CB is a guy that did had several secret basements so he have the means to capture a child there for his own pleasure. If those places are searched and nothing is found and if all media of CB is searched and all that is found is other kind of abuses I guess that it's "positive" in the way that we discard a "monster" from our case. Goes without saying that we can't discard "all monsters" and someone else might have done the same sort of torture/rape to the child we care but at least other possibilities are still on the table while if CB is "guilty" those possibilities are gone.
CB did film the acts of abuse/rapes. Most likely if he were to keep a girl to make her suffer he would film her for sure to keep the videos/images for future use (even if he wouldn't share that he would want to have that fort sure).
If the police does get the USB sticks and memory cards and if they do a proper job of analyzing them if they can't find traces of "missing girls" there we should be more relaxed. Same as if they can't find DNA traces of those girls in the places where he would be most likely abusing them and keeping them captive.
Now I would pick up those USB sticks and memory cards and i would do a sector by sector image of them meaning LBA copy to a image file. Then i would run "raw recovery" on the image file for signature of video and images. That would provide me even with deleted files as long as not over-written.
Then i would do a chip-off on that media, meaning un-solder the NAND chips and use something like Rusolut Visual NAND Reconstructor or PC-3000 for flash and I would recover the data on the memory chips directly even if they were deleted and the controller of the USB pen no longer sends the data to the host PC. From the results i would diferenciate the data.
There is a huge amount of child *advertiser censored* on the net/darkweb/whatever and most of that is known to LE as it's available for directly download for free on known places. Police would only need now to see the images/videos recovered from the pen drives and see if the abused girls on that media are the girls that were abused on the already-known abuse cases / existing child *advertiser censored* or if it's "new content". If it's new content CB it's a "producer" of Child *advertiser censored*.
If what he does have on the pens/cards are mainly existing child *advertiser censored* and the ones that are "produced" are only the ones regarding the rape of the old woman and the "abuses" to the child in the park / daughter of his "girlfriend", whatever and if there are NO CONTENT regarding missing children no where to be found i would say that it's very unlikely that the guy - CB - do indeed commited the abductions. Reasoning is that again - he would be "documenting" the abuses for future use.