Since I loved Extreme-G and F-Zero GX (and I suck at F-Zero, lol)...YES get F-Zero GX.
The subtle difference between F-Zero and Mario Kart is that Mario Kart is a fun game that involves racing while F-Zero is a racing game that happens to be fun. Xtreme G 1 figured that out and made F-Zero + Weapons + Sound Barrier Breaks but kinda lost its focus after that.
The track itself is the hardest part of the game. The AI doesn't really cheat and suddenly get speed boosts 'cause you're in the lead. It's more likely that the AI knows when to boost, when to turn and can avoid hitting the walls unless pushed there (sometimes by other AI cars.) Meanwhile, you're still trying to figure the course out and bumping against the wall can cost you the 0.0001 seconds you need to grab first place.
And then you get story mode. Either the cheesy acting will make you bust a gut (wish it was subtitled...) or you'll go insane retrying the mission for the 7689576985699th time. But in the good way, where it's really hard but you have no one to blame but yourself. Wait no the AI cheats like mad, but hey it's a story mode, of course they have better cars.
Also, it looks great. Remember in Xtreme G when you manage to break the speed of sound and you get the cool blur effect, and the sound dies out 'cause it can't catch up to you? Yeah, F-Zero GX is like that 'cept the music plays. It FEELS so fast.
Sega's AV division did a great job with this game. I totally suck at this game but I still love it.
Get it, you won't regret the purchase.
There is no such thing as a console war. This is the first step to game design.
