I am about to add a timberframe addition to my timberframe house, and at the same time replace most of the windows in the old house, which is wrapped in urethane panels. The latter task will require a lot of new cuts to frame different-sized windows. I'm wondering which tool you all would recommend for this, and whether the same tool is useful for new panel cuts, and perhaps even deep cuts on the timbers.

I'd be tempted by the Prazi attachment, but I'll be cutting through nail- and screw-embedded wood, so unless I get a carbide saw chain, that seems like a bad choice. Has anyone used the Prazi with such a chain, for such a purpose?

Ebay has some older Makita 16" saws, which seems like a good alternative, but I wonder about in-place cuts, as I would need to do to cut new window openings, especially the vertical cuts with a heavy saw. Has anybody done this?

Or should I do the window retrofits with a light circular saw and a sawzall, and do the new panels and beams the way I did them the first time around, with an 8" worm drive and a sharp saw?

Any advice most appreciated.