Is C. Baxter Kruger a Heretic?

A fellowship that I used to attend has had a recent division over the teachings of  C. Baxter Kruger.  I read one of his books, most of which I enjoyed, but some of which gave me problems.  So I wrote to a professor of theology,  Randal Rauser, and asked him about the man.  His reply:

I've never heard of Baxter Kruger. However a 1 minute search shows that he has a book published with Regent College Publishing (my old alma mater) and the book has an introduction by Alan Torrance (Alan is a pillar of Scottish Presbyterian orthodoxy; I know him and he was one of the examiners for my PhD defense). In addition, Kruger studied under James Torrance (father or uncle of Alan; I forget which). James is another pillar of Presbyterian orthodoxy. 

In short, based on a 1 minute review I believe Kruger appears to be a solid theologian as I trust Regent College, Alan Torrance and James Torrance. If your acquaintances have specific charges that are documented, I'd take a look at them. 

I would say the burden of proof is on those who claim that Kruger holds heretical views.

UPDATE:  In a further email exchange, I mentioned that the main concern seemed to center around Kruger's views of the Atonement.  He replied:

As for penal substitution, the church corporate has never settled on a universally binding account of atonement to parallel the Trinity (Constantinople, 381) and incarnation (Chalcedon, 451). So I think your friends have a narrow (and incorrect) view of what constitutes orthodoxy and heresy.