Not necessarily. The Mark VIIs at DL are simply the old Mark Vs with new interiors, nose cones, and detailing. The Mark VI chassis at WDW may be fine. From the work being done, it seems to be the aging beams and control systems that are the problem. Isn't the main thrust of this work to install an automated control system?
In response to OP, monorails slowing down and stopping en route to stations is normal, depending on delays ahead that could easily be due to slow passenger loading. You can't blame them all on maintenance issues. It's normal on rail transit systems everywhere. When the automated control system debuts, instead of stopping between station, the trains will moderate their speed (i.e. slow down) anyway.