I have one of the "140 db" electronic horns on my trike. I almost never use it but it is useful for the jerk who is coming straight at you in the middle of the trail and who doesn't respond to "LOOK UP!". My local trails are not wide enough to get out of the way for someone hogging the center of the trail and oblivious to everything but the pavement below. Most of the time with walkers on the trail I just use my voice to let them know I am passing from behind. Much less obnoxious than blasting them with the horn. They readily recognize a human voice but may not recognize what the horn means.

I wouldn't buy one with all the bells and whistles such as solar recharge and built in light. The simple horn is cheap and I replace the batteries in it about once a year. If the light in the combo deal is going to be solar powered it probably can't be very bright or it would drain the battery quickly. Buy a separate light and get one that is adequate for your needs.