Tim, I read a very learned paper, can't remember where, but possibly on this forum, on the subject of bulb wattage, headlamp brightness and effectiveness. It fully explained in scientific terms how amps, volts, watts, resistance etc etc interact to produce the desired effect, ie light. Way beyond my A level physics !!!
The bottom line was that a higher wattage does not always lead to greater brightness and illumination, sometimes it can have the opposite effect. Having read this I am convinced that the possible advantages that may be gained by changing to higher rated bulbs would be very limited and carry the risk, as you have identified, of damage to circuitry. I determined that standard bulbs was definitely the better option, although the bulb type identified by Richard seems to offer a good way forward, possibly something for nothing, but bulb life might be an issue. Richard, if this proves to be a problem please would you let us know.
Good luck,
Andy
