WE have Used Bosch in the past two years. 2002 we used 30x30 and it was very heavy but extreamly strong. 2003 out entire robot was pretty much built with 20x20 and 20x40 and we also had a linear sliding elevator on bosch.
pics are included below
pros: Flexiable chassis, strong structure, fast assembly if designed and cut right, flexible designing and quick changes.
Cons: Heavy(welded chassis can be much more stronger and lighter then bosch), high maintainance(we had to have 5 ppl with tork drivers to tighten all the nuts after every couple matches) and expensive. wow each t-nut was almost a buck each. tnuts break or bend quickly on over tightening, allignment is difficult at times.
2003
includes delrin sliders
as you can see we made many many many custom plates to hold the extrusions.
WE are planning to use Bosch again this year!