NealR: @exportgoldman I was not aware that the two XT Network USB modems were software upgradable to HSPA+ (aka 21Mbps)
Your right they are not upgradable to HSPA+
The only true HSPA+ card now on the market is the Sierra wireless 306 & 307. The 306 made for XT & the 307 for Vodafone 3G extended. http://www.sierrawireless.com/product/USB306_307.aspx
The Compass 885 is firmware upgradable to 5.72mpbs HSUPA (HSPA/HSPA+) but the down load is no different.
The MF636 is only 2mbps upload and is not upgradable http://www.zte.com.au/main/MF636.htm
The key advantage of the Sierra wireless is the external RF port & the upgradable upload speeds in the future. Thats worth $200 bucks easy over the MF636 but for most people that means little.