I would love to have the Altos, but know I don't have the space. I have seen it demoed several times and my friend has it and I have used hers -- it is a wonderful tool and there is no more waste using it than using a normal ruler and rotary cutter. I have all the rulers i could possibly need (and doubles of some) -- I use the shapecut the most, followed by the 6x24. I have several different triangle rulers of different degrees and sizes and have used all of them at different times. I have the circle things with slots -- sure makes cutting round things easier.
I think Eleanor Burns had an HST square up ruler on one of her shows -- it looked like it would be really neat but I haven't found one yet.