Young Paul
Hopefully the following will give the answers
a) Deancross SID and, Turnberry SID as well, have to climb above Glasgow inbound traffic via LANAK. Glasgow inbound traffic has to be at Minimum Stack Level, normally FL70/80 by LANAK, and 6000ft or below about 8 miles past LANAK. The climb profile on the SIDs is to enable the departing traffic to be climbed safely through the level of the Glasgow inbound traffic. If you cannot make FL100 by 19DME (44before TRN) tell Edinburgh. They will tell ScACC who can then plan accordingly. When the SIDs were designed about 10 years ago the airline operators were consulted and all indicated that there would be no problems in complying with the restriction. Have things changed?
c) It is only designed to climb aircraft above Glasgow arrivals via LANAK. If there are no Glasgow arrivals there is no problem.
d) Answer to the first comment is in a) above
The wrong direction SIDs were drawn that way to separate jets and non jets. As ScACC are not having to separate jets and non jets in the initial stage of flight the jets, although on a slightly longer route, normally get unrestricted climb. Once you have sufficient height more direct routings are given.
Because the jets and non jets are on different routes it reduces the complexity of ScACC operations and gives the airfields a shorter time interval between jet following non jet departures. It also increases the sector capacities in ScACC airspace thus enabling more traffic to fly through them.