Hi Racedoctor,
I play GPL, RBR and... (you guessed it) LFS. I am not a Full Time player because I have to work a lot and other things to do. I love these 3 Sims very much, so from time to time I spend a few Minutes / Hours with them.
Sometimes I don´t touch one or to of the Sim for Months, but then I come back again and play it for a few weeks. As you may see, I am not a fast driver and I need some Time to adapt my Driving style to the different Sims. But all of these 3 Sims allow me to jump in just for a few Minutes or even for a few Hours when I want.
I don´t have to drive 1st Place to have fun, I just love driving and especially on the LFS Servers everytime I find some people who are as slow as me, so I get close Racing whenever I want.
I love LFS because I can do what I want. I can jump in in whatever Car / Track Combination I want and so Track Racing, Rally Cross, Autocross (which is massive fun for me!!) or just toss the car around the Track and do some wild things with it.
If you mastered GPL to stay on the Track you can for LFS too (especially after the last Patch, it´s so much better now). These 3 Sims (GPL, RBR, LFS) are all I need at the moment, because they cover all Racing I love so much.
I am with LFS since S1, but I had around 3 Months pause before the new Patch came and it´s more fun than ever before.
BTW: I have the DFP too, and besides RBR it´s THE Sim which makes the most out of this Wheel. With some cars you have to work like a Maniac if it gets sideways... it feels so great to have 900 Degrees :-)