I have a Holux GPSlim236 working with my Qtek2020i and it does the work. It installed simply on the Qtek and worked well with TTN5.
However, i wonder if i really needed to spend the extra bucks for a Sirf III chipset GPS, as i see no difference in performance between this 20 channel device and other less expensive (with fewer channels) devices.
I Think a 12 channel GPS is good enough for most of the applications (at least for use with TTN5).
This device has something i like (i've seen it on other brands too), which is the battery that is compatible with some Nokia Phones (like the 6600), so you can use the phone's battery if the GPS runs out of battery or use the GPS batery as a replacement battery for your mobile phone ... neat
I have no experience on the globalsat.
My advice is --> Buy the less expensive one!!!