The metabo grinders are really nice tools. The feel, balance, fit and
finish are top notch and you pay dearly for that. The first one you listed
has all the frills like the vibration reduction, the standard soft start
and some sort of electric brake. Never seen the tooless disc change stuff
though- never seen it before. I've never struggled to change a disc, just
to find the wrench.
I've still not fully accepted cordless tools yet though and would be
worried about getting good batteries down the road on the cordless model,
and unless you need portability or have a system of tools that use the
same batteries, you'll be paying quite the premium to lose the cord. The
power is also lower too- they don't even spec it on the cordless models if
you get a matebo datasheet.
Metabo are fine and expensive tools. For that reason I would not buy
the cordless. Being such a fine tool it will last forever. Certainly
long enough to need several new sets of batteries. Even if they are
available, battery technology will have changed and left your 2015
technology behind. You will then have a fine and obsolete tool.
I'm thinking that there must have been millions of Milwaukee (for
example) cordless drills, etc that were working perfectly but were
junked because their NiCad/NiMH batteries made them obsolete.
My opinion is that the abrasive grinding wheel used is as important as the grinder. The Harbor Freight grinder with a good wheel will out perform the Metabo with a lousy wheel. I have gotten some really poor wheels and some good ones from Harbor Freight.
So I would recommend getting a Harbor freight grinder and some abrasive wheels some where else. Then if you find you use the grinder a lot, you might buy the Metabo grinder.
Holey sh*t - 200+GBP for a 4 1/2" angle grinder! I paid ten bucks for
my first one and have added two used ones for five bucks since so that
I could have one each for cutting, grinding and wire brushhing. These
are pretty much throw away items unless you plan to use it more than a
five hours per week.