I find rather problematic the Lore master in higher levels. Most Knowledge DC end up around DC 30, specially in story related knowledge. Not hit dice related. So Let say a bard at level 12 has 12 ranks in knowledge of arcana. And has +2 int. +3 because is class skill, and half her level. 6. You End up with a static 23 in that rank. If she takes 20 you have a raw 43. This is far more that most knowledge requires. And since you can do it once per day and those story related knowledge don't come as often as a swing of a blade. The bard ends up knowing it ALL. I really don’t enjoy placing pieces of information that are just absolutely unknown. It feels like cheating the players. The take ten can be a problem too, because it eliminates the chance of failure, meaning that below certain DC a characters knows it all again, an given a 23 skill. DC 33 seems pretty obscure knowledge. Perhaps level 12 seems pretty high but In 5 level is 22 still. I just want to be able to add certain chance of failure. I am cool with a very knowledgeable person but not nearly omniscient.
IMO, the new rule fixes one of the usages of the Knowledge skills: monster lore. If identifying a monster (and some of its powers, at the DM's option) is 20+CR, the skill becomes meaningful, especially if you award "bits of lore" according to the roll's success (by how many points it beats the DC). In 3.5, even a very knowledgeable high-level character would not be able to know many facts about powerful monsters, which seems weird if a PC is an expert on the area of lore.
As for the non-monster-related DCs, that's a matter of campaign scaling. Perhaps the concepts of "obscure" have to be re-balanced, but I would say that DC 45 or 50 is not rare for items of really "lost knowledge" (like Thassilon in Golarion). Other rare pieces of info are OK IMO to be known by a bard who maxes out a skill in the area, playing a know-it-all character is a thrill at times (and it is one of the few areas where the bard really excels over any other PC class).
Another thing is that a bard is going to know less of skills where he does not put skill points (like the Arcana expert putting no points in Planes or Architecture). If the DM adjudicates knowledge to different areas, soon the bard is not knowing that much, a lot maybe, but not everything.
Plus, you can always give inaccurate info with good knowledge rolls. Knowledge reflects what can be learned through research and study. Just drop in (not too often) cases where the whole world does not know the truth about something and then let the PCs find the truth the rough way...
The Pathfinder Bard can. Their Lore Master class feature lets them take 10 on Knowledge checks at will and take 20 on a certain number of knowledge checks per day (1/day at 5th, 2/day at 11th, 3/day at 17th).
Also in most cases, you can't "take 20" on knowledge skills.
I don't know if I get the SRD right, but it seems to me that taking 20 is always at the DM's final decision... If there's a chance of messing up (risk), then 10 or 20 you cannot take. That makes a bard better off.
Also, notice that he can take 20 "as a standard action". That's the greatest difference, he can remember things faster, without need of long research or interrogation.
Also in most cases, you can't "take 20" on knowledge skills.I don't know if I get the SRD right, but it seems to me that taking 20 is always at the DM's final decision... If there's a chance of messing up (risk), then 10 or 20 you cannot take. That makes a bard better off.
Also, notice that he can take 20 "as a standard action". That's the greatest difference, he can remember things faster, without need of long research or interrogation.
I thought most skills you COULD take 10 or 20 on (barring circumstances and the "chance of failure" thing - but that's a shady area if you think about it, you can ALWAYS fail ANYTHING if you're unlucky enough)... The big thing being time taken when you do so. I see no reason why someone couldn't take 20 on a Lore check if they've got access to some materials to aid their research (much the way a Knowledge skill would work in the same situation) to help jog the researchers memory or to fill in details he or she may not have known just off-hand like the little tidbit of lore that was known...
But, I do like that that kind of ruling should be a GM's call. It makes the game more sensible (especially if you've got "rules lawyers" in your group who will argue about whether or not something can be done because of a written rule in the book regardless of what the GM's saying will or won't work) and it doesn't bog it down with an overly legalistic style of presenting some sort of rule or directive for anything and everything that can be thought of just because some feel it should be "complete" or "cover all bases." Generally I think player and ultimately GM judgment should be left to fill the small areas like this (allowing or disallowing taking 10 or taking 20 on certain skill checks) - and have general guidelines to assist that process. A rule saying a character "under duress" can't take 10 or take 20 is fine (or where there's a chance of failure - though that should be reworded to explain what is meant, like I said, you can mess up ANYTHING so there's no such thing as a skill you'll never ever have a failure with if you use it long enough, there's no such thing as perfection!), and will cover most things just fine.