I don't think GD really had a lot of choice in the matter. British Midland needed more DC9s at the time but couldn't get hold of more DC9-32s as they had wished. G-WLAD came in and was put on the shortest jet sector in the route structure and a "self-isolated" schedule which also wasn't in competition with BA 757s. It was either MME or LBA, and LBA got the 1-11 then MME got the TEA 737 not long afterwards (which used to do a double-drop on the BD337/338 Heathrow on Saturdays via Leeds). Teesside also had a Balair (Swiss) DC9-32 on MME-LHR for a time as well, but I think that was probably 1984/85 so before G-WLAD - that must have been the early days after the Viscounts left.
Both routes switched back to permanent DC9 operation once the next three DC9-32s (PKBD, PKBE and PKBM) had arrived. If I recall correctly, the last three DC9-32s to roll in were the ex-Austrian three, ELDG/H/I.
The noise complaints about GWLAD on the BD411 probably set LBA back at a pretty sensitive time with the H24 application, but in fairness, there were plenty of other 1-11 movements with Dan-Air, BIA, Adria/Tarom and (for a time) Air UK with the 1-11-400 (G-AXMU and G-AXOX) on Leeds-Amsterdam. Those always seemed noisier than G-WLAD.