I reckon it's probably quite expensive. I bought Axminster's portable panel saw jobby, which consists of 2 guide rails (which can be joined for more length) and a bearing guided tool carriage, which you fit any circular saw on to.
I used it for various cuts for builiding a pair of modified 186 horns and apart from the fact that my Black & Decker circular saw has a rubbish mitre gauge, it works very well. I used a table saw for anything less than 460mm wide (max distance from fence to blade) as it's easier and more accurate.
a festool jigsaw with a 2,4 m guide and a few accessories should be better in my opinion.
It's a good idea but....to much part in movement.... I'm fear I'll broken in them in a few times
