I have used both the Sync Master D8010 and D8009 on several shoots and have found it to be quite reliable for syncing cameras with TC-IN while synchronizing DSLR's and Go-Pros at the same time. Sometimes we don't even slate with time-code...just simple sticks with a whiteboard and marker (on one camera) but then the DSLR's and Go-Pros get their own visual time-code from a D8009 or sharing a D8009 between multiple cameras if they are close by each other (and the slate is too far away). It's also been adopted by some local universities in town and they are using it in their programs teaching multi-camera ops with time-code to students. Personally, it has never failed me. On one occasion we hooked it up to a Sony F3 and a Tascam HD-P2 audio recorder and shot for 9 hours without changing batteries (brand-new when we started). We forgot about the Sync Master running on the back of the F3. The little tracer lights are really helpful to tell you when the battery is getting low. After 9 hours we still had 3 lights showing about maybe 50% power on the 8009 connected to the Sony F3. We kept checking time-code more often on the Tascam HD-P2 and I think the battery got pulled out a couple times to conserve power. We also kept a D8010 off to the side running all day on AC power to keep master time code (in case any of the units lost a battery). We synced up the Tascam's D8009 a couple times with the AC-powered D8010 and it was always in Sync with the Sony F3's D8009. At the end of the day, we pulled the D8009 off the F3 and the Tascam and put them next do the D8010 connected to AC power. Then we turned all 3 on and took a picture...NOT A SINGLE FRAME DRIFT in 9 hours. For such an inexpensive time-code product, the accuracy is at least the minimum of the 8 hour spec.
As for durability, we have dropped our units several times without wearing the yellow-boot. Thought for sure we broke them but barely even a mark on the case and they keep working with great accuracy. However, if you drop it hard on the ground to get time-code while shooting a bike race, marathon or sports activity, it is possible to jostle the battery and lose time-code. If you have a chase-car following with a D8010 plugged into the car (by AC power inverter) you can keep all camera operators synchronized to accurate time-code all day long no matter how many times batteries are switched out. Again...this has got to be one of the most versatile time-code units to enter the market yet. Well worth the price in my opinion.
