If I want an infrared image to be B&W I always process from RAW. However, I set my IR camera to RAW + jpg and use a B&W camera preset.
The only reason for this is that the viewfinder is easier to see in B&W than the mostly red IR version.
The sooc images below are just for interest.
The 5 RAW images in the previous post are processed as follows:
1. In Adobe Camera Raw apply a pre-prepared camera profile which is based on a custom IR white balance.
2. In ACR use the eyedropper to set local WB from a neutral area.
3. In PS use the Channel Mixer to swap the Red and Blue...
As I've mentioned I own a full spectrum converted infrared camera so it 'sees' most of the ultraviolet and infrared range of light (deliberately blocked in a normal camera) as well as the visible spectrum. You can limit this to parts of the visible + infrared spectrum by using external filters...
This was an interesting read comparing all the major camera systems pricing for a kit a professional photographer would put together.