Angry pedant stands up for the Maillard reaction here ; searing does not seal the meat....weigh two pieces of beef before and after searing and you'll find the seared meat looses more than a piece cooked at a lower temp....proof indeed......
Loads of tecchy cooking facts about the process around in various sources, but in short the ideal method to get flavour from meat is certainly to sear - this caramalises the natural present sugars that provide the flavouring, through the action of indierct heat on the amino acids and proteins....so sear away at the steak before braising to your hearts content..
If you fancy enlivening your recipes try a few espumas, using hydrocolloids and exploring the awful world of recipes by the like of his magnificence Heston - such as smoked eel and chocolate, snail with beetroot, etc - there is a really interesting resume of things molecular - that is, cookery based on the workings of proteins that are shared by various foodstuffs - hence choc works like eel, so the flavour pairing is a good match (like it or not..) at the site
http://khymos.org
Read it and weep - seriously, you'll weep......home cooking will never be the same if you try the ideas!
And click the 'meat' link for the description of the absolute best way to treat beef - involves boiling in a vacuum then searing........and a comment on the searing argument, too.
Ducks back down and starts muttering about triboluminescence....