Yes they can make a big difference. We have the Wedge-Ramp combo - but if had it to do over again the Wedge is enough. It's designed to help align the g-spot with the normal thrusting angle of your partner on his knees - you end up in a modified missionary position - but that's not all.
It's a neck saver for oral sex - and opens up access for rimming if you like that.
The Wedge also works great for a modified doggie position.
We use to use pillows to assist with some of these things - but pillows cannot compete with the firmness strength and design of Liberator sex furniture.