Kindle and physical books

I bought a Kindle Touch that was delivered just before the Thanksgiving holiday.  Obviously, I am not an early adopter.  There were 3 reasons I finally succumbed. 

1. I used points I earned at work, so it was essentially free.
2. A older book I wanted to read was $25 for the paperback, but $4 for the Kindle edition. 
3. I could get library books on the Kindle, and never have to worry about returning them.

My first two books were Diary of a Player by Brad Paisley and David Wild.  And Winning Low-Limit Hold'em by Lee Jones.  Both were cheaper for the Kindle edition than a physical book.

(I wonder whether there is any psychological significance in the first book a user downloads? )

  I like the Kindle.  It is easy to read.  It weighs about the same as a paperback.  I can read bits of different non-fiction books and it remembers my place.  No stack of books lying around with bookmarks, nagging me to finish.
But I find myself in a quandary.  I like to read the paperback mysteries that Amazon sells 4 for the price of 3.  The Kindle editions are the same price as the paperbacks.  But without the 4 for 3 special.  So it would actually cost me more for the Kindle editions.

In the end, I don't think the Kindle will replace physical books for me.  I have book series that I want to continue collecting.  And I can't justify paying more for 4 Kindle books than for 4 paperbacks.  So, I will get the Kindle edition when it is the cheaper alternative, or if I want to get it from the library.  Otherwise, I will continue to buy physical books.

Which means I'm going to need more book shelves.