Swarovski ME 1.7x magnification extender

Still not 100% sure if it's really needed because I find myself using magnifications around 50-70 x which is what the 95mm scope takes me up to in its original spec.
From 85x magnification upwards there's a fair bit of light lose and obviously drops off more at 120x but saying that it's still usable all the way up to 120x. Obviously weather conditions make a fair difference to this. (sunny or overcast)
Scope does become very sensitive in movement as well.
One point I'd like to make is that my scope is used indoors only and probably affects the performance?

My conclusion was to keep it as the extra money it cost was not massive considering the scope price.
Also it is definitely usable, dropped it 1 star only because of the considerable light lose at top magnification.