I just bought a Mafell Chain Beam Saw for a job involving a lot of big W. Oak. It looks like the Lignatool would quite a bit more awkward and probably not as clean a cut. But I have never used the Lignatool.
I know the Mafell is extremely expensive, but I highly recommend it if the volume of work justifies it. My Mafell should pay for itself in saved time and accuracy pretty quickly.
BTF, I couldn't find the chainsaw attachment on the Fink site. Is it the same company that does biomass boilers?