In my experiences, Ritek (G04) has been a solid choice for blank media (same goes for everyone else's experiences it seems)
No bad burns yet with my Plextor 716A with latest firmware...
One thing I will throw out there, is that you may be better off modding your case, or waiting for the new replacement cases, and using full size media...
Full size media is exceptionally cheaper compared to mini media, and you have the luxury of using the discs you buy for anything you want (backing up DVD's, games which use full size media, etc...) Meaning that you can easilly buy them in bulk without questioning yourself about it...
If you plan to go with full size media, I again reccomend the Ritek discs (I have had better luck with the +R media compared to the -R media myself...) and I also reccomend TDK DVD-/+ R's...Really High Quality stuff for a great price (a local retailer recently had 50 packs for $20!)
Well, there ya go, hope some of this helped you make a good decision
Apparently the GC is extremely picky about not only good media, but a decent burner to burn it with too, i.e. your old Pioneer A03 ain't gonna cut it. I have a un-modified GC using SDloader and my Ritek G04 (Office Depot brand, $2 a piece ) run flawlessly... I've never once had a loading problem.
I've been using TDK dvd+r's since the initial release (oddly, my ritek g04 dvd-r's wouldn't work) and had no problem with them. Now that 1.0 is out, I cannot direct boot from them (unless a later release fixes the +r problem) But ritek dvd-r's now seem to work flawlessly with direct boot. I've also changed from a liteon to a plextor burner, so that may have had some bearing on burn quality. But, you get what you pay for, use crappy media, you will get crappy results. Ritek is a great brand of media, I use them exclusively for my personal movie/game backups and find theyre usually cheaper than most media in stores anyhow
I tried a crap load of different brand mini's when I first got my Viper. The brand that works best is Office Depot. If you use these you will not be disappointed. These are supposed to be the same as Ritek Ridata mini's but from experience I can say the Office Depot brand outperforms them. To date I have had 100% success with them. I've burned over 30 games with no DRE's. I have never seen them on sale but the regular price is 19.99 for a ten pack.
Since cobra v1.0 ive used arita brand fullsize dvdr's all working great, and using traxdata (with g04 dye) mini dvdrs also running perfect. Iv'e tried platinum +dvdr fullsize and had to still use the swap option and it booted.