The CDM has been used in Maine since 1972 and Nebraska since 1996, but, since both states have adopted this approach, the statewide winners have swept all of the state's districts in every election except 2008 and 2016. In 2008, Nebraska gave four of its electoral votes to John McCain, but Barack Obama won a single electoral vote from Nebraska's 2nd congressional district. In 2016, Maine gave three of its electoral votes to Hillary Clinton, but Donald Trump won a single electoral vote in Maine's 2nd congressional district. In neither case did the method have a substantive effect on the election; however, it was used in only two states - both with relatively small populations (and a correspondingly small number of electoral votes).
If the CDM had been used more broadly in 2016, it might have had a very interesting impact in some "swing states". For example, Michigan would have given 11 electoral votes to Trump and 5 to Clinton; Ohio would have gone 14 to 4 for Trump, and Pennsylvania 14 to 6 for Trump as well. Thus, in those three battlegrounds, which gave all of their combined 54 electoral votes to Trump, a CDM-based vote would have gone 39 to 15 in Trump's favor. Of course, California has as many electoral votes as those three states combined; however, Trump would have picked up 7 of the 54 electoral votes in California if the CDM had been used.
If we were to abolish the Electoral College completely, then every close election could involve at least one NATIONWIDE recount of votes. This would cause a repeat the lengthy process we witnessed in Florida in 2000 - but across the whole nation. Close elections could remain undecided for MONTHS on a regular basis. However, if we instead push to have electors apportioned proportionately in every state using the CDM, then recounts might only be required in very close races within individual Congressional districts - a much less onerous process. This would also mean that all states become worthy of attention since even those that go overwhelmingly for one party or the other might still have some electors that are "up for grabs". The Founders' vision would be more fully realized, and the voices of ALL citizens would have a chance to be heard.
There is widespread agreement that gerrymandering needs to be addressed as well. So, I would not want to dismiss what may be the most effective method of improving our electoral process simply because another "broken" part of our system makes it less than perfect in the short term. Let's hope that improving our government is an iterative and ongoing process, and that gerrymandering is also resolved in the not-too-distant future. I suggest you read what FairVote has to say and come to your own conclusions.
What we all certainly agree upon is that the current system is not an effective way of representing the will of ALL citizens, while protecting the rights of citizens in smaller states not to have their rights trampled upon. Get involved, get informed, and take action!