I disagree with nearly all of the points.
Being open source is definitely no warranty
for quality. Many open source projects lack
proper qualified contributors - which makes
progress difficult and even sometimes fixes
chaotic and unplanned. Even in bigger and
more healthy open source projects the work
Is either done by individuals with personal
interests (and disinterests) ... or by
payed teams to work on the project.
There is definitely a lot to ensure before
OpenSource projects provides the quality, focus
and steady progress a dedicated SaaS Team
can provide.
This is also not a mutual exclusive decision. The software
behind a SaaS could be OpenSource and the service
can still offer enough value to be good, while
at the same time giving the opportunity to
get features into the SaaS by contributing to
the Open Source project.