For me, high stat characters creates several problems that I have seen first hand when DMing and from reading the boards here and on WOTC D&D boards.
1. They can more easily take on and defeat monsters and encounters of the appropriate CR/ECL - - which leads to gaining xp faster and therefore leveling faster
2. Combat goes much faster, so much that the monsters rarely get to use more than one special ability
3. Not much tactical flavor if combat goes too fast (no time for flanking, AOO, last ditch dashes by cleric to save tank with last minute cure....)
4. To challenge them you often have to throw more and/or higher CR/ECL monsters encounters at them
- - combat may last longer, but even more so leads to PCs gaining xp faster and therefore leveling even faster (I see many DMs complaining their PCs are leveling too fast)
5. Magic, start going over the suggested baseline of magic for the PCs level, only further compounds the problems. You have to carefully watch the magic items you place in your adventures.
- - now you have high-stat PCs with uber magic items, now you really got to work on increasing or raising the monsters CR/ECL to really challenge them
I would much rather run a 25 PB (or 28 PB tops) game,
- - using the monsters straight out of the book
- - even monsters just one CR lower are a challenge, and more often get a chance to use their different abilities
- - with longer battles, different classes have more opportunities to use different abilities and shine in their right
- - slower xp gain and slower leveling, gives players more time to game-play with their current class abilities...
- - have ample leeway to create and place interesting (not specifically the big six) magic items
- - I as the DM have more time to focus on other story/adventure details, besides trying to determine the right CR/ECL of monsters necessary to challenge the party
- - and lets me run a more grim and gritty medival fantasy campaign, which I find much more enjoyed to run - versus - the Super Friends meet King Arthur