So, I have now moved to Squarespace. It wasn't too bad to get my content over, although I suspect that some of my links from the past 7 years are probably broken. Squarespace tries to rewrite them properly but I would be very surprised if it's 100%.
I'm not sure that there is an immediate huge benefit, but it's nice to think that I don't have to worry about keeping my WordPress site updated with all the latest patches (which I wasn't actually doing).
One thing I am not super excited about is that the Archives are no longer expandable and grouped by year. From what I can see, my options are weekly or monthly. Hopefully there is a workaround which I don't know about. I think Squarespace is supposed to be coming out with their new release soon, so if there isn't in version 5 perhaps there is in version 6.