Thing I have found with multitools is, you have to hold the tool firmly (nowt sexual like) If you hold it loosely the tool vibrates instead of cutting the material.
It does CGN, Took a door frame out yesterday using my multi tool. Bloody thing had been fixed with thunderbolts.. Almost impossible to remove (took me over an hour to remove the old frame) Well not quite impossible, but an hour to get an old door frame out !!!!!!
Just jesting JJ I was using one yesterday for quite a long period , I was vibrating by the end of it, but if whatever you're cutting isn't secured, you do get the tool buzzing. Possibly down to type of blade used too...
Re the starlock blades. Likes of saxton can't do them because Bosch and Fein have locked the patent down tight so only OEM blades available at much higher prices.
Used the Dewalt 18v for 2 years and not had any issues, other than stock Dewalt blades being rubbish. Very expensive rubbish too. Best I've found so far are the 'Smart' branded ones from Toolstation - both bimetal and fast cut styles outlasted the dewalt and cut better out of the pack. Tried Faithful blades and they dropped their teeth faster than a granny in a toffee factory; bi-metal was comically bad. Biggest drawback with the tool is not being able to set the speed and lock it on. Fast blade change is very handy though.
Bosch GOP2000 250w tools on offer at £69.99 (inc) http://www.screwfix.com/p/bosch-gop2000-250w-professional-multi-cutter-240v/5423f