Dave, yes, the price on ebay went up...
I did mine exactly the same way as you did, just used stainless steel bar to move the roller up and bent it towards the trunk a bit - enough to make some more space for the chair travel, but not too much not to prevent the roller lock from working properly. I lost about 1-2cm of chair travel. A colleague in our club in Poland did it the way you are planning on doing and it works and fits great. it was just about making a stronger anchor point with a nut in the chassis and making a bit of a passage on the edge of the wooden floor (taking 2-3mm of wood on the distance of 6-7cm on the edge).
Yes, there is abit of tension you feel on your shoulder, especially on longer drives. Belt holder helps ease it a bit. The roller also makes some noise when you pull the webbing - but this I found quite funny rather than irritating. But feeling of safety is much much greater.