...or better the
Topeak one. I've used the Minoura SG1, SG2, and the Topeak Bar X-Tender.
The Topeak seems the most solid, then the shorter SG2, and then the long SG1. For some reason even though it's bigger, the SG1 seems to use smaller nuts and bolts in it's construction, which seems bizarre. It may be that Minoura changed the design, so maybe the current SG2 also uses the smaller parts. The Topeak seems the most solid, especially if the load is heavier.
I've had a GPS and fairly hefty Exposure lamp on the Topeak, and it's taken it better than the SG1, which started to work loose after not much mileage.
I quite like the Spacegrips, but the Bar X-Tender seems more flexible in positioning options, and more ruggedly solid.