F3G,
I would have thought my comment was self explanatory, and did not mention "being out of control".
If you are maintaining a glide slope using pitch attitude, you will be varying the airspeed, ergo if you have been asked to maintain an airspeed by ATC you are not meeting their request.
I cannot comment on flying large FW, but would tend to agree with the remarks about flight directors given the response time of turbofans and the subsequent a/c response. When I was first taught to fly FW it was in the Bulldog and there was never any question of using the controls in their primary role. As I recall, maintaining accurate datums (such as airspeed) was pretty high on the instructors' requirements.
Ironically, the a/c I fly now has a 4 axis autopilot that uses different control laws depending if it in 3 or 4 axis mode. In 3 axis it uses pitch to control Alt or V/S or IAS, in 4 axis it uses pitch to control IAS and power to control Alt or V/S (or glideslope)