Infrastructure training

As a former technical trainer who worked for a world renowned training provider (I won't mention their name because I'm going to remove them), I would recommend that you go directly to Infragistics. If you go to one of the reputed training providers, they will probably sell you training on the subject. They will grab one of their technical instructors and then train on that topic, and then that person will come out and teach you. So, the instructor you get is not a subject matter expert. There is always a chance that there is a teacher with rich experience in Infragistics, but I really doubt it.

The company I worked for regularly assigned me to teach subjects that I was unfamiliar with. I'm a .Net developer but would have to teach crazy actors how to make money for a company when they didn't have .Net classes. For example, once I had to teach Excel advanced Excel. When I got to the site, I found out that what they really wanted to know were Excel PivotTable Tables, and my company had just sold them an extended Excel class. I have never used pivot tables before and did not know how they work. I've ever come off like a tool! More importantly, the client didn't get anything useful from my time. Do you know how often I use Excel? An hour or two a month. But since I was a senior technical trainer, I had to know everything there is to know about Excel in one week. I want to say,that you will get someone like me; competent enough in some technologies, but probably not Infragistics.

Having said all that, I am also wary of getting training from Infragistics. If you are an advanced user group, you may already be more competent than the trainer who is sent out for training. I would make sure you detail the specific topics you want to study, the importance of those topics, and make sure the training contract you signed contains language regarding this (IANAL). Make sure they understand what you want and that you will be dissatisfied with anything less. It will probably cost you more, but it could mean you are getting a senior coach who can at least research the topics you need before they arrive.

Edit:

To be clear, I have no experience at all with teaching Infragistics or the company in general, other than using some of their controls in a past project. They may have the best training in the world. I am making a generalization about vendor training. As I mentioned, I used Infragistics controls in a WinForms project a few years ago and thought they were very nice.