My belief is that since your home office network is your network, and under your control, it should actually be more reliable than the network that your office-bound associates a) enjoy or b) suffer. If you operate from a home office on anything more than an occasional basis I think that you should give some serious consideration to maintaining redundant sources of IP connectivity. This is especially true if you rely upon VoIP for your office phones, as we have here for many years.
Redundant IP connectivity can be achieved in a variety of different ways, each with advantages and disadvantages. Performance and price vary widely depending upon the access methods available in your area. For us the best solution has been to use Comcast Business Class cable as our primary internet access, with backup provided by a dry loop DSL circuit from Covad.
It’s important that your two sources of connectivity are different modes of connection, in our case cable & DSL. We could bond a couple of DSL lines and achieve higher speeds, but we’d be susceptible to a single mistake with a backhoe taking out both of our circuits.
I’ve walked down the street, examined the lines and know that the copper goes south down the street while the coax cable goes another direction. No one silly mistake will take them both down.