Tis a bit of an RC-biased thread there, Jim, so you'll excuse me (I hope) if I address the balance somewhat.
The Big Question is: Is your NT Bible the accurate NT Bible ... or is it a Protestant Corruption ... or is it a Catholic conspiracy? You Decide!
As Didier alludes to, the King James Version contains the same books as the Douay. Further the JWs don't claim that the Protestants further corrupted the Bible, being content to accept that it was an improvement to have a Bible in English, instead of confined to Latin.
On the point of authentic teaching, surely you're not going to sidestep the fact that the Reformers were Catholic Priests with an RC education and all the Orthodox documents available to them? These weren't unlearned men, and the schizm occured within the [RC] church, not as an assault from without.
Given that this was a period of time when all sorts of wacky scientific beliefs were sustained by the religious (RC) authorities, I'm sure you'll agree that there has actually been progress, rather than regress in the advancement of thought, and this was bound to have an affect on theology as well. While there are some denominations that eschew solid doctrine and theology, this is not representative of the whole group.
Scottish Reformed Presbyterianism has been one bulwark of learning that does not simply change doctrine at whim, and has been responsible for some of the greatest theological minds worldwide (or at least in the last 400 years). This is also to be expected, given its RC roots, even if there is a modern antipathy to said roots. It also had a system of church government that is rooted in Pastors, Presbyters and Deacons, with congregations, councils and synods related to one another, rather than "independant". In fact the only thing it is lacking is a "Holy See", which it holds in common with the Greek Orthodox.
As a further sidebar to the Reformed churches, while they hold to the canon of 66 books being inspired, they also acknowledge that there is some merit in the "subordinate standards" of other documents and books, including the Apocrypha and Creeds. You will find many of the "Divines" refering to them.
Just my 2p - no skin lost