If you require to increase all engine thrust reduction altitude due to obstacle clearance, what are you meant to do if you lose an engine? Now there may well be airfields where you do have to do this to achieve all engine terrain clearance and have a specific escape procedure if you do lose an engine, but I haven't come across one yet.
I would perhaps expand on the comment above with regards to stating that thrust reduction altitude isn't operator specific. We have standard operating procedure written down (UK airline / A320) that we shall both reduce thrust and accelerate at 1000' AAL unless stated otherwise. Yes it is true that certain airports ask you to modify these for noise abatement in which case we do, but for most destinations I fly to, we don't modify this. More commonly we increase the acceleration altitude though due to obstacle clearance (but keep thrust reduction at 1000' AAL).
The only case I have come across where thrust reduction altitude is increased is specifically for noise abatement (more noise closer to the airport, less further away as aircraft has achieved a greater climb gradient).
In summary I would suggest for obstacle clearance you should be thinking more about acceleration altitude than thrust reduction altitude. Acceleration altitude is where we lower the nose, accelerate to our climb speed whilst bringing in slats/flaps.