I don't want to revive the Festool vs home-brewed debate, but thought I'd share my experiences. I haven't used the EZ system, so I'm only going to write about Festool vs my jig.
I used a jig such as described by ALF and Scrit before buying a Festool circular saw and guide rails. On the whole I do get far better results now:
1) The saw's build quality is superb. It's very well balanced and smooth and chews through 18mm ply so effortlessly that it does feel like it's gliding along the rail. This is undoubtedly the biggest factor in the difference between the new setup and using my jig with my previous circular saw (a Hitachi - very robust but nowhere near as refined). However once you have the Festool saw, you might as well get the guide rails too.
2) Cleanliness of cut and chip free edges. Again, can be largely attributed to the saw itself. The rubber edging on the rail does seem to get "tighter" to the sheet than my home made jig did, but user error can possibly be blamed there!
3) Accuracy. I have not had problems with aligning two rails end on end - maybe my work is too low tolerance! I find I often stop and start the saw as I progress through an 8 foot cut - usually at least once, sometimes twice (working on my kitchen floor does not give my the room to walk around the sheet). I've generally not seen any inaccuracy or stepping resulting from this - again maybe more due to the saw's plunge action than the rail?
4) Angle attachment. The angle attachment is not so useful. I might need a bit more practice with it, but right now I am marking out the line and aligning by eye rather than using it.
5) Clamps. When working on a table, being able to clamp from underneath (and therefore having no obstruction to the saw's travel on top) is a handy feature.
In general, I think the Festool circular saw is an excellent product, with the guide rails just adding to its feature set. I do find the Festool setup more foolproof too (i.e. I make less stupid mistakes and get better results with the same amount of user ability).
Perhaps the best comparison is that I used to cut as close to the final size as I dared with the Hitachi and then run a router against a straight edge to get the finished cut. With the Festool I cut directly to the final line. I am sure the more experienced woodworkers here could have got good results with my previous kit - the Festool stuff flatters despite my lack of ability!
(off topic, I also bought the jig saw and CT-33 extractor, which I'd recommend too)
The EZ system looks very interesting - I like the horizontal movement of the router attachment, seems very useful. If I was to start from a tool-less shed, I think my decision would be driven by my choice of saw.
Ian
