There has been some chatter that Ghosthand cubes are "F type" cubes. Personally, I use an FII as my main speedcube, and have used a GHI and GHII. Had I ordered a GHI or GHII before I ordered my FII, I would have been satisfied. My cube progression was: storebought(5 or so of these)->Type A/B(Hybrid)->FII. The Hybrid might have had some potential had my excessive use of Jig-a-loo not killed the plastic.
Honestly if all you want is a fast, smooth turning cube, that can cut corners, I recommend any of the following: GHI, GHII, FI, FII, AV, Haiyan, Haiyan Memory, Dayan GuHong. I'm sure I've missed some but those are by far the most popular.
At your speed you will not see much of a difference in the Ghosthand and F type cubes.
I recently received an AV and Dayan GuHong, but I haven't been able to test them out yet (been busy all week).
I recommend you visit:
Speedsolving Wiki - a lot of great information here ranging from hardware, solve methods, and other great links
Stefan Pochmann's Speedcubes.net - information about various twisty puzzles and associated items (like timers)