The folks at AllChurchsound tend to oversimplify things.
Yes, split mono and/or L&R ldspkr systems can produce combfiltering. A LCR (left, center, right) system can reduce combfiltering. A "point source" system may not be the most appropriate design for many churches.
Downlobes may be reduced by selection of specific crossover slopes, gain adjustment, delay and/or physical adjustment.
For those folks who are aware of these choices (and their compromises) or who just simply want to have the best possible sound, it is impossible to recommend the most appropriate methods without thorough programming and design development. You should contract with a qualified consultant who has experience (and references) in sound reinforcement system and acoustic design for HOW. This consultant should be very well trained in sound system measurement and optimization, as this is a very important part of the process.
BTW - as long as you are reading speaker system design technical references, take a look at the papers on JBL's website, on Frazier's website (
www.frazierspeakers.com), read Jim Brown's papers on stereo speaker systems (
www.audiosystemsgroup.com) and google on relevant words. These may enlighten you or possibly confuse you.... but they will also point out that things are not as simple as some folks think they are.