To the point:
I don't have anything against the NDP even though I don't like their leader. Still, I'm a bit reluctant about a merger. Electoral cooperation? Sure. A merger? I dunno.
I'm reluctant for a few reasons: first, Canada would become a two party state. Yes, there would still be the Bloc, but they're not really in the business of governing Canada. If the Bloc performs well, but the campaigns are fully decided in ROC due to only having two choices, does this isolate PQ? Maybe not in reality, but in perception. What are those ramifications? Conversely, what if we can't get a solid decision from ROC and the Bloc has the balance of power? Do we really want a party who doesn't believe in this country controlling the agenda? The last bit sounds a bit like late 2008 Harper anti-coalition scare tactics, but it should be considered (especially since there would be one less player).
Additionally, the Liberals have rebounded from doing poorly before: Turner to Chretien. I know those were different circumstances when the right became fractured, but is this the only way forward? Something to think about.
The most compelling anti-coalition reason from my perspective is the least self serving as a Liberal. I like having the dippers around. Yes, their current incarnation would likely not gain power anytime soon, but I think we need those smaller voices that are willing to put ideas out there that the "blue chip" parties can't. Turning into a two party state virtually eliminates this, and ideas from left field that might end up being beneficial might be silenced. Even though the NDP has never governed, they've punched above their electoral weight, and Canada's benefitted from this. Put them under a party umbrella, and compromise might eliminate some of their shine.
I get that Harper's unsavoury. I know he'll do everything he can to destroy other parties, but is the electorate passive enough to let him? What about the press? Even though I don't respect, I can't fathom them sitting around like a Harper cabinet minister -- completely bound and gagged.
I like the idea of electoral cooperation, but a merger? Use whatever Liberal stereotypes you want against me, for me but Liberal is Canada. I love a strong and independent Canada.