Either way works well. If you have the original lens hood, you probably won't need to put on the lens cap too.
The lens hood is very well made and the metal barrel creates a distance from the lens thus protecting it from scratches.
The main purpose of the lens hood to me is to protect the lens barrel at the manual focus ring. My friend's RX1 has started to get paint loss at the edge of the lens barrel due to knocks and friction when you place the camera on the table, or when you accidentally knock on the table or wall. The paint near the edge of the lens barrel drops off easily exposing silver colour, or dents. Quite ugly.
With the lens hood on, it helps to block and cover the edge of the lens barrel, and thus protect the paint work.
Have checked out the compatible lens hood (Made in China type). Material looks firmsy with rough edges and paintwork is quite poor. Not sure whether it will last or will it scratch the camera instead.
The original one is made of very high quality metal - like the other RX1 accessories, it is Made in Japan and paintwork, edges, all smooth and bling bling.
Of course, quality comes with cost - $249 for lens hood!
Agreed that a hood on the RX1 will have added protection, and minimize flare as well.
Gotten a 3rd party hood from ebay for ~$15 including shipping. Quality wise it's rock solid, made of metal with smooth edges. Doesn't feel a bit inferior to that of the original one, but it's a screw in type so not as elegant if you need to add some filters.
Would love to own the original hood but just can't justify myself paying 200+ for a piece of lens protection.