The set is mixed metric and SAE that differentiates them. I think they are very well thought out sets and the higher cost is justified by the storage and organization. My main criticism is the ratchet designs if these sets included low profile pear heads with long and maybe flex heads I would have pulled the trigger on some sets.
I usually rule out kits that have both metric and SAE, unless it's come "DIY master kit". Aside from a 1/4 for aftermarket hose clamps, SAE is not going to be showing up in any roadside repair. For better or worse, I see "also includes SAE" as a poor marketing term reaching out to people who may not know much about repairing cars. I don't really want any more SAE, so why buy a kit with it?
YES I am aware this post will be quoted by someone who daily drives a 100% SAE car, and calls me a fool and a jerk for insulting SAE. Or the guy who insists his 100% SAE tractor only breaks-down on pavement, which is technically the roadside, so everyone needs a full SAE set.
For 99% of cars I have worked on professionally, SAE was nowhere to be found, outside of aftermarket hose clamps, and the occasional inner dash stuff on domestics. My "roadside repair" stuff, being a mechanic, may be different than most. Hell, trade out the SAE for a $20 volt meter.
$300 seems kinda steep. Why not buy a gearwrench kit; although I will say is all the tools LOOK top notch. What I do like, is the satin finish; when are other companies going to start marketing that? How are the pliers to work with? Nothing worse than NEEDING pliers, and having crappy ones.
Like yourself, I feel naked without an emergency tool set in my trusty 05' Duramax, so I took a gander at the various kits they offer and the one you have seemed to be the best choice. Being I drive a Chevy, 
I should never need them, but I do have a few friends with Fords 
, so they'll come in handy for sure!