I replaced the HDD on my B2 some time ago because the HDD started showing some of the signs that it was failing, an SSD was, from the reliability POV, a simple fix. It was, with a bit of advice from Paul and Martin, a 30 minute DIY on the kitchen table effort. Somewhere on this forum I documented what I needed to do.
I have had several HDDs fail on a variety of different computers over the years, but have never seen an SSD fail.
To me reliability is the main benefit.