Re: Nakhla i really like this stuff but...
It could be. I am ignorant to the Mizo line (isn't that the washed line?) but the Mandarin is more than likely not washed. Tobacco which isn't washed has a higher nicotine content than washed tobacco. WHen first starting to smoke hookah my first bowl of Nakhla made me slightly sick. In a few bowls you'll be fine though, no worries =).
For smoking shisha to slowly get used to nicotine, i'd start off with "pansy leveled nicotine" tobacco, such as Starbuzz. After starbuzz i'd go to Romman/AF, then start hitting up Nakhla. After Nakhla, Tangiers is amazing if you can get it right.
As for HH/HF, can't say i'm a big fan of their tobacco. I've had some alright smokes, 1-3 good ones (I did thoroughly enjoy blueberry pancakes and peanut butter), but the majority where simply "mediocre."