I had commented elsewhere regarding this and someone asked my to leave the comment here.

My issue with the "benchmark" that was run is it will favor Jetpack. Basically they assume that the features in Jetpack are all desirable but that isn't the case for every site. In the benchmark they replicate 5 features from popular plugins (also note this doesn't mean those plugins are the best choices. Often popular plugins add a lot of bloat as well. They are popular because they try to be all things).

Under this scenario the site will definitely load more slowly because all the infrastructure of Jetpack will be loaded once and the infrastructure of the 5 other plugins loads replacing features of Jetpack.

One of the complaints about "bloat" when discussing Jetpack is all the features that aren't necessary and the fact that new features can be enabled during update. This typically requires a second plugin to be installed so that new features are off by default.

A more valid benchmark would be feature to feature. If you use Jetpack for a single feature like the social sharing buttons (which many people do because Jetpack has great social sharing buttons) you could do a benchmark testing that single feature against a stand alone social sharing plugin.

We did this at copyblogger.com. We had the social sharing buttons from Jetpack enabled on the site and found it was adding a good bit of lag to the site load times. We built our own solution with several key features to make the buttons load more quickly and we stripped out as much code as possible to ensure there was little bloat. Then we benchmarked Jetpack with the social buttons enabled against our plugin and found a huge improvement on page loads, especially in the archives because of some lazy loading features.

Of course, there is going to be a tipping point that makes the single feature benchmark inaccurate for a given site. If a site is using several of the features in Jetpack it makes sense to use all of the features as required by the site. At this point the benchmarks done by Brute Protect apply because you are using enough features that the number of stand alone plugins can end up resulting in slower load times than Jetpack.

I no longer do freelance, but when I did I often did site optimizations for customers. There are many instances where enabling Jetpack and disabling half a dozen or more plugins could produce big gains. I also found instances where disabling Jetpack and using one or two plugins produced big gains. Most of the time my first goal in optimizing a site is evaluating each plugin with the plan of disabling it if at all possible.

It's important, IMO, to treat each site individually. Sometimes Jetpack is the right tool for the job. Sometimes it isn't. Using a single benchmark to overturn a "myth" makes for good television but bad science.

PS don't let my last comment fool you. I love Mythbusters even if their science is horrible.