Looking at the Devil Rat from the Critters 3 sourcebook, I find its stats are:
body 2, quickness 5 x 3, strength 1, charisma 5, intelligence 2/5, willpower 3, reaction 5

In 4th Edition, they are:
body 2, agility 5, reaction 5, strength 1, charisma 5, intuition 5, logic 2, willpower 3, edge 2, magic 3

Almost no changes between them, which is unfortunate because I expected there to be 2/3rds as much in 4e as there is in 3e (like it says in the recently-posted character conversion guide). Is this intentional, or poor copy+paste editing in the 4e sourcebook?

I'd like to use some critters from older books, but I'd like to keep them on relatively the same power scales as before. How would you all suggest I do this? Keep the stats relatively the same, or feed them through the character conversion guide and base their strength from there?

I guess this comes back to the old "Are 4th Ed characters weaker than 3rd Ed" debate. If they are, then I shouldn't convert the critters' stats. If they aren't, then I should, because logically the critters would have "lost" attribute points just like their PC counterparts.