As a general rule I normally do not write to NTFS Volumes from OS X on a daily basis however I do on occasion and at times write some individual files that are large, 10 to 50 GB and have yet to have any issues. I normally do not run VM's from the NTFS Volume under OS X although today I played around for a while doing lots of disk activity seeing if it would be problematic and it wasn't.
Now I did not use the same methods you did to enable write support for NTFS under OS X and though I'd share with you what I'm using. On my newest MacBook Pro I installed just two things, OSXFuse 2.5.5 (2.5.6 has been release since I install 2.5.5 however I've not updated it yet) and the commercial version of Tuxera NTFS for Mac 2012.3.6.
As a general rule I normally keep Tuxera NTFS for Mac disabled and enable it on the fly when I need to write to an NTFS Volume as it is something I do more as the exception not necessarily the rule. However since over the last year I've written a couple terabytes of data, especially very large files to NTFS Volumes from OS X and making sure MD5/SHA1/SHA256 checksums match and have yet to have issues and I consider it safer then using ExtFAT for my use.