Interesting piece. I haven't combined track in any permanent layout, but I have some 'temporary' layouts that use moth MTL and Marklin track. I found that IBL's roadbed is a useful base for the unadorned Marklin track, and after reading your piece I measured the IBL. Of course it's soft and a little variable, but I get around .090", just a smidge taller that your recommendation. The realistic color of the IBM roadbed makes the flat gray of the MTL look even worse, though... Gotta paint one or the other.
As for filing, I haven't fount it necessary on my temporary layouts.
--- In firstname.lastname@example.org, "john_ztrains" <john_ztrains@...> wrote:
> New York: Monday, November 23, 2009:
> Ztrains is happy to present our newest Z Scale Basics article titled "Mixing Track".
> In this article we show you our technique for quickly combining MTL Micro-Track® with Marklin sectional track. It's a simple process and we've photographed the steps for you in detail.
> John Cubbin
> Ztrains: Z Scale (1:220) Model Railroading Information