As for the correct answers / knowledge situation - well.. maybe it's not unfair, but what I'd bicker about is why they were the only team of the series (I suppose I'm wrong, but even if I am, they were amongst the minority) to answer 2 correctly and earn no more clues. All I'd argue is why is wasn't kept the same for everybody - even if it appears blantantly obvious, by adventurers code or otherwise, which objects to take.

Yeh, I'm still a bit baffled by the door-monster idea. I'd imagine, as you say, the 'requirements' on each level are more difficult - but it was still far easier having 50 / 50 chances along the way than having to answer two of Merlin's riddles, and then a real stinker of a level 3 riddle to have a chance of winning in S3. (My op. anyhow.   )

as far as it can be told, the door monsters only required a single truth to pass on.

(with apologies for double-quoting)

According to the series guides, you needed one answer to pass in level 1, two for level 2, and all three for level 3.  As you noted, though, I can't find anywhere this is mentioned throughout the actual broadcasts... wonder where this idea came from

Thinking of Kelly's quest - even 2/ 3 correct responses did not gain them the knowledge required to escape level 1 (unfair)

Not unfair at all.  I'll have to dig my knightmare books out to check, but I'm fairly certain that it's part of the adventurer's code.  If there are alternatives to taking gold and silver, then unless directed otherwise you should take them, otherwise it's seen as a sign of greed (even if you're intending to bribe people with it).  Several teams died in series 2 as a result of shunning seemingly useless items for gold/silver.

Yes, there was a small element of this in S4 with Oakley and the weeping doors. However, several teams got to escape Oakley's questioning, and as far as it can be told, the door monsters only required a single truth to pass on. At that, they were all 50/50 chanced, and no information amount was levied on correct answers - so, Series 3 for me was more heavily dependant on knowledge. Thinking of Kelly's quest - even 2/ 3 correct responses did not gain them the knowledge required to escape level 1 (unfair) - but, apart from some convincing encounters with door monsters, I'd say the dungeon of  Series 3 was a whole different prospect for Dickon's team. The teams here had to answer off their own backs.. not a 50/50 chance in most cases, and - thinking to a post I've just written recently, the eye shield made life often a lot easier in S4 for directional purposes. Series 3 had nothing to make directions any easier.

My answer to the question/proposal would be possibly, but I honestly think not.