I compared iGetter 2.9.4 with Folx 5.0 and since I posted a review on the Folx page, I think that the results may be interesting for the iGetter users as well.
I downloaded 5 times with each app, iTunes12.4.1.dmg from the Apple servers (alternating Folx and iGetter, both with two threads). The result is:
1. iGetter is faster than Folx with a difference of avg. 48 sec. I measured the elapsed time with a chronograph app, because Folx has no Elapsed time value (except by extracting dates in the the Log).
2. iGetter speed is stable and Elapsed+Estimate times are correct. Folx speed varies so much that I can't see any usable speed/estimate time value. Folx downloading stalls and fluctuates constantly.
3. iGetter shows a lot more information about the finished downloads (including referrer web page, avg.speed, elapsed time, finished date). Folx shows only file name and size.
4. All iGetter functions can be tried in the unregistered version for unlimited period. Folx Pro features (i.e. more than two threads, speed control, scheduling) have no trial.
You may compare both apps for yourself, but iGetter seems more mature than Folx (comparing the features that exist in both apps).