Hmm you need to look at a number of aspects as it sounds like you are a single person operator doing small systems. I have been there so! How are you going to support the processes, remotely or turn up when they fail, can you client do some of the support himself (IE restart an SSIS package/job). Corollary, how critical is the load. Another issue, does your client expect to play in your dirt patch, will he want to learn from your SSIS, is he one of those to want to inspect the code? And do you want him to. This pros and cons, he can help support himself and he can also screw up the system dramatically. Personally I always move the file BEFORE processing it, I do the processing from the archive folder. I also prefer a winforms app as I then have complete control and can walk the user through a restart/reload etc. This is a preference only as both SSIS and app can do all the functionality required (SSIS can poll the folder every #n seconds/minutes using the job scheduler)
Never underestimate the power of human stupidity RAH