I am also in the market for a glass 5 wt. I have been lurking on a board devoted to glass rods and will pass on their collective wisdom (ie opinions). There are many good options in 3 or 4 wt blanks from Lami, Diamondglass, Steffen Bros, and Mcfarland. When it comes to 5 wt the favorites seem to be:

Mcfarland 8 ft 3 piece 5 wt for a slower progressive action. Maybe more of a 4/5 wt (a 5 wt out to 50 ft). Some think it is very special, but it will require a stroke suited to cane not graphite.
Steffen 8 ft 3 piece 5/6. Probably a true 5 wt and more of a general purpose rod. A little faster and stronger, with a nice glass feel,but still not for casting over the horizon. Steffen's 8.5 ft version of this rod is said to be a 6wt.

I have a Franke/Steffen and I have only heard positives about Mcfarland's quality. Both companies offer models not shown on their web sites. These are only hearsay opinions!