It is stated that trucks with weights of 11,794kg GVW or less are exempt from the requirements of the Hours Of service regulations.

What does this 'exempt' exactly? Are they completely exempt from running a log book? exempt from adhering to the 16hr shift rule?

We run everything from 1 ton vans to tractor trailer units and some drivers operate different class vehicles within a 24hr period. In speaking with one of the NSC representatives, I was told that a driver operating a vehicle under 5500kg GVW did not have to run a log unless he was in the sleeper berth over night? As well, if the driver switched from a 5000kg GVW to a 14,600kg GVW vehicle in the same day, he would then have to show in his log the drive time for both vehicles?

I've heard nothing of this type of an exemption the only exemption I am aware of was for over and under 190? kms, and the under 5500 exemption the under 190 was removed with the new HOS regs. You may be able to find a more comprehensive explanation of the HOS rules as they apply to city p and d drivers here.

Link below is for Bulletin #4-2008 Sept 23,2008
Re: Record Keeping requirements for Local Drivers under the Hours of Service Regulations.

viewtopic.php?f=8&t=554

I found the aforementioned exemption on the CVSE website:
http://www.cvse.ca/ctm/Com_Circulars/2007/071128-CC-03.pdf
even though it states vehicles under 11,794kg GVW are exempt from complying with HOS requirements, it seems it is not true.

The GVW rating plays a part in our operation because our drivers run everything from cargo vans to single and tandem straight trucks to tractor trailer, sometimes in the same day. We have a weird niche.
Our hours of operation are affected by Marine weather, Dept of Fisheries PSP openings, Packer boat ETAs, Market demand, BC ferries schedules/waits/changes/failures and of course receivers hours of operation. A lot of hours can be burned just by the truck being on time and then having one of these variables(which can fluctuate daily) bite us in the ass.
To add to it, we haul live refrigerated seafood that is due on prepaid flights to asia.

For the most part, we do not have trouble operating within the bulk of the HOS rules, it is the 16hr shift rule that is our thorn. It's not the On duty time that gets us, it's the off duty time because it is not consectutive.

Thanks for the link Dan, that does help clarify. I called a couple of the scales to get info in piecing this puzzle together and each scale has a slightly different answer, lol.

In any case, it seems to me, be it the driver or the carrier, a log (or accurate account of hours) has to be kept in every situation regardless of GVW. In our case it would be easier and likely more accurate for the driver to log everything himself.