Starting a nano is harder than doing a larger SW, The bigger you go the easier it is. Due to the impact in such a small water volume a lot can go wrong, Don't let that put you off though. It's all about learning, I mean I drove right into FW and it hurt but after awhile I learned the ropes and moved onto SW.
There's a lot of things to take into account when playing with SW, It's not all about ammonia, nitrite and nitrate now. You have to take in how much salt is in the water, a good hard PH level etc.
Cycles in marines are shorter due to using live rock as a filter, if you use live sand too you can end up with stable results after a week maybe less.
It's entirely up to yourself if you want to take a bash or not, don't let others put you off. Just make sure you have a large wallet for this.