Yes I think a pair of Bose L1 is by far the best choice for a church, especially when there is unlikely to be a dedicated audio engineer. I think any reputable mixer will work well with that system. A conventional system is much more likely to have disturbing feedback issues which is the last thing you want to have to deal with during a church service with no-one sitting at the mixer. As Diki points out there are many problems that can occur on a church stage.

Plus a pair of Bose L1 and a good mixing board comes in way under $10,000 so allows for other necessary extras like quality microphones and stands which could add up if a number of mics are required.

I can only speak from my own experience and as the Verger of our own church here in the UK I oversee all the functions wedding,funeral,public and concerts. Our church has fantastic accustics as most of the old churches do and like most it was built somwhere around 1200 AD of stone and timber of course with mods down the ages . We just have a simple public address system of 60 watts (with wireless loop for the hearing impaired) this carries wireless mic's for speech and sometimes solo vocalists. The system also caters for output CD playing if needed. Our organ is accustic pipe and the only instruments that ever require a mic are accustic guitars. This system is quite adequate for us but of course not necessarily so for all others or different situations.