I'm just following up on this if anyone is curious.
I used a Kenko Color Meter KCM-3100 to take readings.
After measuring the colour temperature of a variety of light sources that I've got down in the darkroom, I was surprised to find out that most of them were warmer than the Ilford ideal range, which is between 2856k and 3000k. I got that number from Ilford Technical service, who were (as usual!) most helpful. If a lamp has a warmer colour temperature, it will produce less contrast with variable contrast paper. Primarily I use VC paper, so this was a concern.
Here are some of the readings:
Durst Atlas 300W bulb - 2350k
PH211 75w - 2640k
PH212 150w - 2590k
PH213 250w - 2870k
Saunders colour head - 2750k
Omega colour head - 2920k
Point light source on mid setting - 2280k
This is by no means a proper exhaustive test - I just checked what I had on hand. I work in a group darkroom, and we've got 12 Omega D5s with PH211 bulbs, and the figure above is an average of those. They were consistently below Ilford's recommended values. Not as warm as some of the other sources though. I was mainly interested in addressing the Durst Thorn 300w bulb and the point light source, as that's what I am personally using. I figured I would add a cooling filter to the system and see how it behaved. I used the following mired shift calculators:
http://www.pointsinfocus.com/tools/mired-calculator/
http://www.leefilters.com/lighting/mired-shift-calculator.html
I bought some Lee gels sheets - 202 and 218 blues - and put them in my filter drawer. I measured the lamps again, and was able to get both lamps to around 2900k, which was just where I wanted.
I made a series of step wedge tests, with and without the cooling filters, and with both the Thorn bulb and the point light. I made them at grade 2, grade 5, and with no filter at all. In all cases I got a significant boost in contrast with the cooling filters. Less than a grade, but more than half. This was right across the board, which was great news. I'm not knocking IC-Racer's approach for testing in post # 2, but in the end, that method didn't tell the whole story.
Why fuss around, you ask? Well, it was a bit of a rabbit hole. I was initially curious about the colour temperature of the point light source, but as often the case in the darkroom, one thing leads to another. I mostly do split grade printing, and I want my grade 5 filter to deliver the most contrast possible. It suits my style of printing. When I'm burning locally with a grade 5, I'd like it to be as hard a contrast as possible, if you follow me. The point light source was a logical conclusion to that train of thought.
I suspect that the situation I was in was not the norm. That Thorn bulb of mine has got to be 20+ years old, maybe more, and I gather that bulbs tend to get warmer in colour temp as they age. The point light is quite warm on low to mid settings due to being run through a variac. Both these sources were well off the ideal. If I was using one of the PH211s that was a touch warm, I don't think I'd be concerned at all.
Hopefully I won't have to do this again!