I have a 400 foot climb at 6% grade towards the end of my ride. I have a 19ah battery on my CCS that is typically at 60% SOC when I get to this hill. The performance of the bike shows degradation towards the top of the hill. The CCS is a great bike but it is built for speed (on the flats) and is not a great climber. I could consistently go up this same hill on a Stromer ST2 at 25mph but on the CCS I'm usually at 21mph and slowing towards the top. The Stromer never slowed down and did this climb with a 30% SOC. Alternatively, the CCS will go 30 mph on the flats (for a while with a strong charge), where I had to really work hard on the ST2 to maintain 28 mph but I think much of this was a software limitation.
As for how fast you can go, that depends on.....how much you peddle, how much wind is coming at you, how hot or cold it is outside, etc.... It should be noted that the CCS/X are high cadence bikes. They perform better when in a lower gear and you peddling faster. The CCS will bog down more when in a higher gear with a lower cadence.
I do think the CCS/X can handle your ride just fine, you will likely need to be pedaling a bit more as you progress up the hill.
Disclaimer:
Your definition of bogging down might be different than mine. I ride aggressively and anything short of top performance I consider to be bogging down.
ps. I'm about 65kg and carry another 10kg on the back rack.