So you would save staffing costs buy burying the line for the full length? Or building underpasses at every cross street? Or what? Elevated guideway? I don't see how you would save money in the medium term.
No.
What I have ALWAYS stated would be the best option for the Eglinton Crosstown is to combine it with the existing SRT using the existing SkyTrain technology. The TTC is going to be spending nearly $1 billion on changing the SRT to LRT. Changing it to LRT is actually the most expensive option and has the lowest capacity of subway/metro, SkyTrain, monorail, or LRT. This is because LRT is the only one of those technologies that requires a complete revamp of the existing RT stations due to the overhead power catenarys which requires "raising the roof" of the stations.......expensive and time consuming.
No other city on the planet would tear down a rapid transit system and replace with one which will have lower capacity and yet more expensive to run. The only logical cost effective option for the Eglinton/Scar is to extend the SRT northeast to Malvern and west along Eglinton. They could elevate the northeast section and elevate along Eglinton until roughly Don Mills. This would result in twice the capacity, a far more reliable system, better service levels, and cost much less to operate. Much of the needed funds for the whole line would come from the savings of not having to revamp all the stations and not having to build a totally new LRT garage/maintenance centre. Simply improve the short turns to accomodate the MK111 cars and add the heating mechanism on the rails and Bob's your uncle.
Vancouver's SkyTrain has proven itself to be very cost effective, reliable, frequent, fast, safe, and with the new MK111 trains very comfortable, smoothe, quiet, and pleasant.
Would I use the SkyTrain if starting from scratch?....No but because much of the line is built then it only makes sense to extend the line. The reality of the situation is that Eglinton requires a completly grade separated line. Due to the savings of not having to spend a fortune {and a lot of time} by not changing the SRT to LRT, Metrolinx could very easily to get a company to chip in a hefty amount to create a seemless, grade separated Eg/Scar/Mal line to help build and run it as they would see real returns due to being automated.
It's funny, people continually denegrate the Canada Line due to it's small stations and those are very valid concerns. At the same time, Toronto will be spending 3 times as much on a line that will have lower capacity, speed, reliability, and be more expensive to run. This is why Vancouver has expanded it's rapid transit by 70 km in the last 25 years and Toronto has by only 7km.