Wasn't any connection or ftp software problems my end, AFAIK - and the problems may just have been related to, as you say, temporary heavy traffic on your server, as it seems OK now, and I was getting "connection timed out" messages.
I just tried FTP'ing into one of your domains and it worked for me. Which program are you using to FTP into your website?
uploading one file at a time - or editing on line - is very very slow, and often fails.
I've never experienced that, do you get any error messages or anything?
Plus the sites are slow to load as well.
I just checked with one of our Engineers and was informed that that it does appear our Hosting server is under quite a bit of traffic. They are trying to hunt down the domain right now.
This issue may also be related to your inability to connect via FTP.