Well, I would argue PR in its various guises reflects the will of the electorate better than a first past the post system, and the criticism of not being able to vote for a presentative doesn't even hold for the parliament in Greece. The system does seem quite complicated by the looks of it though. But then again, Greeks have over 2000 years of experience with democracy...
And I don't understand why a grand coalition should be undemocratic as such, if this has been the only way to form a governing majority, it does reflect the will of the voters. The problem with a grand coalition, particularly in Germany, is an marginalised opposition, as many functions, including speaking time, are proportioned to the share of votes.
Change can be achieved even without parties being part of a governing coalition, the example is the German Green party which managed to put their goals onto the agenda of most other parties long before they became part of a government.