Nice necro...
On your build: why the focus on Wis? Wis is not needed, from an optimisation standpoint, but can be nice for RP reasons. You're never going to Spot or Listen to much anything even with medium Wis, and will saves are covered by three classes with high will save bases. Spend the points on Int and Con instead, with Dex a nice third option (ray spells, AC, some skills, ref saves... INITIATIVE!).
Reflex saves are the least important saves you're going to make. If you want to be better at them, get an item. Failing one merely means you're taking a bit of extra damage most of the time - damage isn't horrible, because you're probably going to be able to mitigate many other damage sources (such as a Barbarian or Dire Rhino charging you) via defensive spells (Fly, Invisibility...). That said, Insightful Reflexes is not a terrible feat choice, but looks slightly worse than you could get. Or at least, slightly unneeded.
Spellcasting Prodigy is likewise a suboptimal feat. Try finding something with a little more oomph. In my book, any feat you spend a precious slot on ought to let you do something new and exciting, or at least provide a numerical bonus that actually makes a qualitative difference. Practiced Spellcaster is good, but besides that, you may want to look into Improved Familiar, Craft Wondrous Item, Improved Initiative, Flyby Attack. Or if you're going the Metamagic route, Arcane Thesis (ask if you can retrain this, though!), Split Ray, Sculpt Spell, Extend Spell, Metamagic School Focus (needs Spell Focus).
You will be a little feat strapped, so consider playing a Human or Strongheart Halfling. Those are great choices for an arcane caster anyway.
That all said, your success will likely come down to what you actually do with your character in play - tactics and spell use are very important when playing a caster, especially one as complicated as an Ultimate Magus. You're never going to run out of spells at this point, but your highest level spell slots will be severely limited. Also, you'll be limited by the amount of actions you can take. Consider burning lower level slots (esp. from your Beguiler side) on all kinds of marginally useful stuff in between combats and becoming your party's go-to for general utility, that's great fun and lets you do stuff all the time, not only in combat. Be creative! The Beguiler spell list can really be exploited for great value in many everyday situations!