First, let me say that I've tried this app on its own (and many others) and it does not allow me access to the file structure of the 500GB HDD I use.
Sure, the app "mounts" the HDD, but there is more to accessing external memory than mounting the drive. The device needs to be able to recognize the drive format, and that is what is still missing from your suggested app. There will still be no access to the drive, and the "Unrecognized Format" error will remain.
Second, if you read carefully, the app documentation says...
---- ATTENTION ----
This will only work on rooted devices and requires a kernel that has the ums enabled. ... It also requires a kernel with ums enabled and modules for ntfs/hfs/hfs+ etc.
So, you need more than root; you need a kernel which supports NTSF via the ntfs.ko module. The native kernel in the Tab does not.
And, as I have said, I've actually enabled the ntfs.ko module, and gotten this to work after weeks of trying every app out there. It's really pretty easy to do, and if anyone wants more info... just let me know.
However, if you actually get this app to work on a Galaxy Tab with the native kernel - and by that I mean the kernel which came originally with the tab and not one that was included in a ROM you might have flashed (FYI - I'm on Task's Galaxy V11 with Pershoots 2.6.36.4 available on XDA) - I'd be interested in knowing how you did it.