The guide number is measure at 35mm FL (35mm format).
If you are to get a 60CT, get the CT-4. One of the features unique to the CT-4 is power ratio settings, from full to 1/256 in 1/3 EV step. I believe that the CT-4 is the only one that has low trigger voltage. It's been a while so I can't remember the exact value of the trigger voltage, but it's low enough that I use my 60 CT-4 triggered by the hotshoe of my K10D and K-7. With my 60CT-1, I need a Wein unit.
Recycle time of the 60 series from full-power is about 6 sec. with 6V SLA battery. With a 7.2V Li-Ion (
link) the recycle time is reduced to about 5 sec..
In comparison, the 45CT is about 1 stop less powerful than the 60CT series (60/45 = 1.33; 1 stop = 1.4), with a Quantum Turbo battery or the like, a 45CT can recycle in about 2 sec.. You can use the Quantum turbo battery for other flash units. Of course the 45CT can take 6 AA batteries in case of emergency, or when you don't need short recycle time.
One advantage of the 60CT and 45CT is that they are built like a tank, at least compared to the Pentax AF540FGZ.