Regrettably, I may have spoken too soon in my criticism of GMP; more regrettably, I can't delete the previous post.
As it turns out, it may not have been the fault of this map program at all; in fact, I'm almost certain it was not. I foolishly yielded to the false assumption that if two things happen simultaneously, then there must be a cause-effect relationship. This is a fallacy, something the reptilian mid-brain does that we - or I, anyway - have to overrule with my thinking brain - when I remember to engage it.
So I owe Nick (the developer) an apology for the harsh post. I really can't say how good or bad the program is because I never had the chance to use it. I suspect that it's like a lot of apps and plugins: it has its strengths and weaknesses. But, again, I do not know. I spoke in ignorance and frustration and was unfair in doing so.
But I do know this: Nick stayed up late trying to help me resolve it (there's a big time difference between South Africa and South Texas). Based on his commitment to make things right, I would recommend the product to anyone looking for a map plugin. He also refunded my $15 for the pro version.
Again, I was wrong to post earlier based on incomplete and incorrect information. I know nothing about the app and that should be taken into consideration by anyone reading my first comment.