JBL Crossover Help

I recently bought a pair of JBL JRX 115 speakers for my P.A. system. The HF Driver (4 ohms) is very harsh around the 3-4 khz region. I've read reviews online from alot of websites that they use a 6-9db cut on their EQ in that region just to get it sounding good again suitable for the human ear. It is weak at 10khz and beyond. I read about the selenium driver d210ti. it has an accurate frequency response up to 20khz, and have seen it on you tube as a great improvement, crystal clear highs, not harsh and painful to the ears. The problem is, is that the JBL 2412H-1 HF driver is 4 ohms @ 50 RMS watts. The selenium is 8 ohms @ 80 RMS watts. I'm pretty sure, but someone correct me if I'm wrong. Now, what I've read about crossovers is that ohms are everything when dealing with networks. I heard that when you are dealing with a 4 ohm speaker, and a crossover designed for a 4 ohm load, that 50/50 percent of the power is divided to the speaker and crossover, lets say. If I install an 8 ohm speaker in the 4 ohm crossover, that will be 4ohm with a 8 ohm speaker, the crossover will be getting 33.333% and the speaker will be getting 66.666% of the power, since 8 of the 12 ohms is the speaker. since the JBl driver is 50 RMS at 50%, and the selenium would have a 66% power going to it, not 50% like the JBL, that would be a 16% increase, resulting in 8 more watts going to it, 58 watts. Do you think the crossover will be hurt in any way by doing this change? and please let me know anything about this, I'm just learning. I tried to look for the slopes on the crossovers but I can't find it anywhere. I know it's @ 1.6 Khz. Thanks.