Let's take a look at what's good about this...
1) Timely notice of prize changes! With more than a month's notice, we all know exactly what's at stake in the first four Regionals of the season.
2) More prizes! Everyone is getting MORE out of this, which is a step in the right direction.
3) Prizes adjusted for inflation! It's been over eight years since the first $300 award, yet inflation and airfare have done harm to the award's value. Now that we have tangible prizes at the $500 range, OP could theoretically avoid editing the prize for a decade, yet still give the players receiving the stipends something of real value.
Now, what's wrong here?
1) The distribution of prizes between age groups. While P!P's taken the stance to treat Masters differently from Seniors and Juniors, you can argue that this is the opposite of what would've been most productive. The end goal of all these prizes and whatnot is marketing/getting more product sold, so how does it encourage participation by giving stipend prizes in Regionals to the age groups least capable of appreciating their worth, yet no new stipend prizes to the age group that would undoubtedly be most affected by it?
I think those are some pretty fair generalizations to make. Of course there will be exceptions, especially in the Seniors division, but not offering up stipends to the Masters seems like a huge snub to the largest age group, whose players would be much more eager to attend three regionals and buy more product if even one person had the additional $500.
2) In the grand scheme of things, the prize pool is still smaller for Masters than what it was in 2010 and 2011, and only slightly larger for Juniors/Seniors.