Hello FossMaNo1 (and Chriscom),
I think a lot will also depend on the current and future use of your facility, and the people who will be working with your equipment week-in and week-out.
My wife and I have traveled to a lot of different churches, performing with our L1 Model 1's or L1 Compacts (depending on venue size.) I also volunteer as sound tech for one of the rooms in our large home church. Our church is large enough to have a full-time tech staff, who have worked with pro designers to implement a large sound network. They also have the patience to work with volunteers (like me) who know how to move faders but may not know all the ins, outs, effects and routing of the top-end boards, and how they are interconnected with each room's stage boxes. Also, sometimes a guest speaker may show up with a laptop needing an A/V connection.
A fixed installation provides a stable environment. Many different hands may touch the mixer during the week for worship, prayer services, teaching services, meetings, etc. It helps if contact can be limited to the mixing board and an A/V interface, and not having tons of other wires and knobs exposed to the curious. The staff has saved a "scene" in the mixer, so it can be "reset" for critical Sunday morning service. The "flown" speaker placements are designed for proper coverage, and are not subject to moving or walking out the side door. (Yes, that can happen in a church.) Our church does have a couple of portable systems for versatility, as you do with your L1 Pro8 (which is perfect for that need.)
When visiting other churches, we always bring our own L1 system(s), unless it is a "festival" situation with multiple artists using the provided or contracted system. Lots of smaller churches may not have a sound tech available for an evening service, and you never know if or how you might connect to it, or how it will sound, or how we might (and probably would) mess it up if we were to use it. Plus, our normal audience is, frankly, older than our regular Sunday morning's younger worshippers. Our L1 Model 1's could never complete with our church's installed system at its Sunday morning levels.
As far as your $50,000 quote ... get more than one proposal! Talk to other churches, especially those similarly sized and somewhat larger. Make a list of your priorities, and plan for the future. Have the contractors clearly explain why they propose certain equipment. Will your speakers work with headset mics or podiums, do you want your worship team to grow, how much "messing with knobs" do you want the people on the platform to deal with vs. someone more experienced in the sound booth?
I'm not saying that L1 systems won't work for you -- you just have to be good stewards of your church's funds. Good luck, and I'm hoping more folks chime in on this post!
Does that help?