For my birthday, I received Don Ringe's From Proto-Indo-European to Proto-Germanic and I've been reading it while taking the train in to work.

I find that even though I'm not in academia any more it's refreshing to spend some time perusing hard-core historical linguistic geekery, particularly since I've never really delved into PIE with the depth that I should have. I suspect that many Anglo-Saxonists tend to skimp on their study of the linguistic pre-history of English, especially the earliest stages.

Sure, they can confidently talk about Grimm's and Verner's laws, which they probably teach every time they run a History of English course, but can they go beyond what appears in the introductory textbooks that they teach from?

I'd like to believe that they can, but past experience suggests to me that of those whose home is in English departments, only a small subset have the ability. Admittedly, Anglo-Saxonists are far less prone to the phobia of confronting technical aspects of language than some in English departments, but

One reason for that gap is that most graduate programs in English (at U.S. universities, anyway) simply don't force students to acquire the necessary technical skills to understand even books like Ringe's, which is designed as an intermediate-level handbook (not completely introductory, but not intended only for Indo-Europeanists).

Here's the background Ringe suggests is necessary for his book:

I expect readers to have acquired a basic grounding in modern linguistics, without necessarily being familiar with the details of any one theory. In phonology, I presuppose an understanding of the principle of phonemic contrast, familiarity with systems of ordered rules, and an understanding of how surface filters differ from the latter (but not, for example, familiarity with Optimality Theory). In morphology I presuppose a general understanding of case, tense, aspect, mood, and the other traditional inflectional categories, as well as the concepts of productivity and defaults. Though I have little to say about syntax in this volume, what I do say presupposes some version of (post-)Chomskyan syntax. (p. 2)

To me, that suggests you could get by if you had mastered all the material in a typical introduction to linguistics class, although I suspect this would need to be supplemented by some additional reading in phonology.

But how many graduate students in English, even medievalists, take even a single linguistics course? I've long felt that all English PhD's ought to have some familiarity with the technical underpinnings of English, even if their own research interests take them in different directions.

Medievalists certainly get more of the technical stuff than others, but much of it is unsystematic, old-fashioned philology, and doesn't necessarily equip them to understand the work of their colleagues in other departments.