If I understand your question..
There really is no way to edit a package outside the GUI. You can try notepad or any XML editor but I can almost guarantee pain, and lots of it.
It is possible to edit a package programatically but this requires even more knowledge than using the GUI..
The learning curve for SSIS feels pretty high, however, once you get it..
You were talking about changing databases, this is really easy. However if field names change in a dataflow that could be a problem, the metadata about field names are set at design time.. I believe CozyROC has a tool DataFlow Plus (I think) that might do it.
I looked at that SSIS rant page and disagreed with most of his complaints and partially agreed with some of the other people's complaints. Many of his complaints seem to step from either misunderstandings or outright unwillingness to research the solution.
Long story short, I have yet to see any other homegrown ETL tool written in .net or other language outperform SSIS in throughput. could it happen, sure, is it likely, nope..