DigiCheck is very efficient for recording from RME Interfaces. It writes all the tracks to a single file (a big one). This means there is no issue with threading. When you record 20 tracks with Sonar, it creates and writes to 20 Wave files. 
 
When you record 20 tracks with DigiCheck it records to a single file (which it gives a wave extension). 
It saves as it goes so if you get interrupted (power failure) you don't lose it all.
After you hit stop, you hit Save to write the file to a new location. You cannot Start recording again until you clear the old recording. Don't clear the old recording before you've saved it under a new name.
When saving, after you select a file name, you can choose

• a multi-channel File - good for saving it off during the show. Say at set break. You don't care about splitting it yet, you just want it saved off.
• stereo files - good if you want stereo waves exported. I never use this.
• Single Channel Files - splits the multi channel file into separate Wave files (same mono waves you'd record with Sonar). You only choose one file name, but it appends numbers to the file names to keep them distinct.

 
DigiCheck is definitely the easiest on system resources. I can record substantially more data concurrently with DigiCheck using the same hard drive than I can with Sonar because it is more efficient to write all the data to a single file.
 
** I don't use DigiCheck's Global Record feature if I'm comping. Obviously, when working in a project where you are listening to synths from within Sonar, you need to be able to hear them. In some cases, I have used DigiCheck and recorded both with DigiCheck and with Sonar. I don't record Midi with DigiCheck (idk why, but I haven't found out how). I do sometimes mix in Sonar with Global Record if I'm doing some sort of performance. I can mix everything to a pair of outs and set them to Loopback and record them using DigiCheck. Then I can record a performance for a video-screen capture. I don't want my headphones on 10, so I don't record the headphones track. I make a separate track which I mix much like the headphones using the TRIM settings inside Total Mix.
 
Remember you have compressors and EQs you can use in your UFX. Make sure you have the latest drivers and versions of Total Mix and DigiCheck. The April version of Total Mix is really cool (see video in my signature).

Boydie
I think you have got the 2gb file size limit from the FAT32 hard drive system format

I would therefore just make sure that the hard drives you are recording to are the NTFS system format, to alleviate any of these worries

It is easy to convert your hard drives to this format - Google is your friend here

Good luck

Not exactly - the 2Gb limit on standard wave files applies irrespective of FAT32 or NTFS. The limitation is because the size field stored in the wave header is a signed 32 bit number that can only represent up to 2GB. As mattelus indicated, SONAR will automatically detect an overflow and convert the file to a Wave64 format wave file that doesn't suffer from this limitation. So wave file size is not something to be worried about - its handled automatically.

Noel, is this true in Sonar 8.5 as well?  Windows xp 32 bit.

I just pulled this from the 8.5 Reference Guide (pg. 240):
 
I am "assuming" the Waves-64 format was introduced with SONAR 7, but Noel would know for certain (that version reference is not in the X3 guide).

*dupe*

Sixfinger
Noel, is this true in Sonar 8.5 as well?  Windows xp 32 bit.

Yes. You can easily verify it for yourself. Create a dummy project with a single track which is long enough to exceed 2GB at 44.1Khz 24 bit. You can put a single clip at the end of the track to do this.
Bounce the track and look at the wave data folder. You should see a wave 64 file with a .w64 extension created...

:) For the first time in my life I feel well informed on this aspect. Thank you all.

The Windows XP (as opposed to Sonar) file size limit depends on whether the drive in question is formatted to FAT32 or NTFS.

FAT32 has a maximum file size of 2Gigabytes, NTFS of 16Terabytes minus 4KB. You need the drive you are recording to to be NTFS.

To check what a drive is formatted to, right click on it in My Computer. The file system type is on the general properties tab if I remember correctly.

It's been a very long time since I used XP, but I seem to recall it is possible to convert a FAT32 drive to NTFS and retain the data on it, but how reliable this is I have no idea. Failing that the only option is to back up, reformat the drive to NTFS and restore data/reinstall XP and software as applicable.