At the time of my writing this, it's on sale for $US4.99!!! An absolute bargain! So take the opportunity to get it cheap NOW!
[edit][timestamp=1418993558] The $4.99 deal ends in approximately 29 hours and 7 minutes from the time of this edit. ;)[/edit]

Here is the link to the steam FSX forum Topic Microsoft Flight Simulator X: Steam Edition Change Log

I have the Captain Sim L-1011 and L-1011F working in Microsoft Flight Simulator X: Steam Edition (which I will write as FSX-SE from here on), but I forgot some things I need to do, so when I finish my first short flight in it (in around half an hour), I will do those things that still need doing. ;)

Later on, I will try each Captain Sim product for FSX in FSX-SE, and (hopefully) figure out exactly what needs to be done to get them working. Dovetail Games make no guarantees that ALL 3rd party addons will work, so it might be up to the developers to get behind it.

So far, FSX-SE seems to be very frame rate friendly, but it's hard for me to tell because it is very bare when compared to my FSX with heaps of addons, like Orbx FTX AU, NZ & Global scenery.