Appreciate everyone's input. Interesting points of view for sure. Nothing is for sure on implementing DCS and Legacy/TMCC control on same vintage Gilbert track/switches.
So, upon still further thought, I’m going to start out my DCS experience with just the DCS Explorer, PN 50-1035. I am aware of its limitations on control features compared to full up TIU/WIU combo and that it provides a max of 6 amps for track power and has a 5 amp fuse in it and is limited to max of 3 Protosound engines at one time and doesn’t communicate with Legacy/TMCC systems, doesn’t provide unique engine configurations, no lashups, etc. That’s all ok to me for my intended use. I am comfortable using my Legacy/TMCC remote for only Legacy/TMCC locos and using the MTH DCS Explorer with smart device only for the two MTH ProtoSound 3.0 locos that I now have. I expect the engines will do well in their respective control modes at constant 17-18 volts track voltage as long as I keep total track current comfortably below the Explorer 5 amp fuse rating. I'll send power as follow: transformer > my 5 amp inline fast blow fuse > DCS Explorer > Atlas 215 SPDT switch array > Track loops. I'll wire the DCS Explorer ground output to my overall ground bus terminal strip for the overall layout.
So, how much current does my layout usually require? I just ran my two MTH F-3s that have ProtoSound 3.0 using conventional AC transformer throttle controlled voltage to the track. I had them running off of the same Z4000 single throttle up to ~14 volts at a good speed with incandescent-lighted passenger cars on one engine and freight cars on the other engine. I had them running on 2 separate track loops. With that, my Z4000 digital amp reading is ~2 amps. I then ran a TMCC Lionel American Flyer steamer with freight cars at the same 14 volt throttle setting off of the same Z4000 throttle on my 3rd track loop along with the 2 MTH F-3s. The Z4000 digital current reading was still only about 2.3 amps with all 3 trains running at a good speed at ~14 volts. I didn't want to go above 14 volts because the MTH F-3s would've jumped the track on my R20 curves. But 14 volts was enough to power and control the TMCC steamer via Legacy handheld remote. Operating either the steamer whistle or the F-3 horn upped the total track current from the transformer to ~3 amps while the horn/whistle was ‘on’ then dropped back to ~2.3 amps again after disengaging the horn/whistle. All of this using only one of the Z4000 throttle power outputs switched to all 3 of my track loops at the same time via my Atlas 215 SPDT switch.
So, looks like I have ample margin for current draw less than the DCS Explorer 5 amp fuse. So, I’m pretty sure that just the DCS Explorer will give me a good taste of DCS operation on my vintage Gilbert track/switch layout while still enabling me to run multiple Legacy/TMCC/ProtoSound 3.0 trains at the same time at a constant 17-18 track volts using either the Legacy remote for Legacy/TMCC engines or the DCS software application for ProtoSound 3.0 engines on a smart device like iPhone or iPad. I just need to closely watch my track current draw. I don't generally run my smoke units so that lessens current draw too. I can always electrically bypass the DCS Explorer via my Atlas 215 SPDT switch array if/when needed for higher current draw situations like running my conventional locos.
I plan to wire the DCS Explorer between my Z4000 and one of the inputs on my Atlas 215 SPDT switch array. I already have a 5 amp quick blow fuse wired inbetween my Z4000 and my Atlas 215 SPTD switch array; I’ll let it there. That fuse does blow quickly when I have a derailment like crossing into a Gilbert switch that’s in the wrong position ... have done that a few times. I believe that retaining my 5 amp quick blow fuse between Z4000 and DCS Explorer will cause my inline fuse to blow before the DCS Explorer 5 amp fuse which is my preference. I have a bunch of spare 5 amp quick blow fuses for such derailments. I could use a 4 amp inline fuse to avoid blowing the DCS Explorer fuse. Will figure that out later. My track layout has operated fine with my current 5 amp inline quick blow fuse for up to 3 trains with incandescent-lighted passenger cars and or freight cars. Typical current draw has been running ~2 - 2.5 amps with increase to 3 amps total when operating horn/whistle.
So, I'm optimistic that this lower cost DCS Explorer investment will show me if DCS will work ok on my vintage Gilbert track loops and Gilbert switches. I am optimistic that my Legacy and TMCC locos will operate simultaneously with MTH Protosound 3.0 locos using their respective controls as long as I keep total track current through the DCS explorer comfortably below its 5 amp fuse rating. I'll try it with one loop; if ok, will add 2nd loop; etc. If DCS signals prove to be insufficient for one or more of my multi-loops, I'll drop the DCS Explorer and be content with my good-running Legacy/TMCC controls.
I will report my experience upon getting things up and running.