500 SPG points for MAGC is decent (not great, not terrible, but decent). I choose it every time. I haven't stayed at a Marriott property in almost a year (even though I'm MR Lifetime Plat) as I switched loyalty to SPG last fall. 500 MR points for MAGC is crap. I doubt that I'll choose that option unless they decide to enhance it on parity with SPG.