It's a hard problem, which the COMPlus team knew when they started out. During the early pre-release period, there was a then-NDA-only project, Project 7, which gave grants to people trying to port both commercial languages like perl and academic languages like scheme. I was at Northwestern, where we got a Project 7 grant to work on a scheme implementation (under Ian Horswill, done by Pinku Surana in my group) and scheme language service (done by me).

We provided a lot of feedback, but it's tough for a group of a couple of students (or in the case of Perl, one commercial dev) to keep up with the then massive-breaking-changes drops we'd get from DevDiv every 3 months or so and provide feedback when it was on stuff that was, to the developers, around 6 months old. Often, by the time feedback landed, it was "too late" to incorporate because of product cycles and got postponed. Or the stuff we'd request was a dupe of "add tail call instruction" which had been postponed long before any of us got started in Project 7.

I say this as somebody who then graduated and then went to work in DevDiv for the next 7 years, where I was treated very well, so I certainly have no axes to grind on that front :-)