I personally love Globalist benefits and feel Hyatt offers the best consistency for their top tier vs others. However with that being said, consider what it will "cost" you.
I.E, will you not make a status at another chain that you frequent more often? Is the $500 spend just to make Globalist for 1 year, if so will you get $500 worth of perks in return?
If it was me, I wouldn't do a mattress run, if I thought I couldn't keep it, but we all have different goals.
Have you considered the Hyatt Credit card? You'll get Explorist, plus an accelerated path( 5 night credit, more with CC spend) towards Globalist.
That's my 2 cents