Kreative: The Fabfilter line is excellent, especially the Pro line. The Pro-L limiter is wonderfully transparent and is seen by some to be a standard (many users around here compare other limiters against the Pro-L standard); the Pro-Q and Pro-C are leaders in their fields. I own the FX Bundle, but bought it last Christmas during that sale which was before the release of Saturn (so I don't own Saturn). As someone else has pointed out, FF has these sales twice a year (Summer and Christmas). You really should download the free demos and try them out for yourself.
CPU Load? In another thread you were concerned about how a tape sim plugin drained CPU on your DAW. Downloading and testing the FF demos would make sure for you that your machine can handle them. They have never been a trouble for me, but I have a newer I7 with 16 gigs of ram. To be honest I don't even recall how heavy they hit my CPU, but given your concerns in that other thread you should demo the plugins to make sure.
One last comment not for you but for novices to FabFilter plugins. They are designed for the Pros. They are designed to be used by skilled, experienced persons who have a good understanding of these types of plugins (compressors, limiters, gates, EQs) and how their settings work.
Fabfilter provides very few presets for the Pro series line (they do provide more presets for Timeless). Again this is not a problem for persons who already know how to use the plugins and are willing or wanting to start from scratch with EQ or a Limiter or a Compressor. However, if you are looking for a myriad of presets for every possible track senario, then you need to know that these plugins don't come loaded with a lot of presets. [Edited: I have no idea why I wrote this. So I have stricken it out. There are some very good presets for various instruments and mastering/mixing. They are good starting points to get you in the ball park and then you can tweak and adjust to fit your needs. Sorry for this blunder.]
Returning to quality, yoropal has summarized it well.
"If one had what they call their "FX Bundle" you really wouldn't need anything else except a great Reverb and the occasional single purpose "oddball" plug."
My advice? Download the demo, see for yourself, and you will probably buy and use these excellent plugins on many tracks and mixes.