If the main thing you need to do is solve puzzles then the EE (not PE) is an awesome size.
If the main thing you need to do is have this device in a pocket at all times and carry around, you may wish to consider the PE, though in truth, I think it might be too small to provide a good puzzle-solving experience.
Please note that something seems to be happening with the company today, so I encourage you to find some members here who might be thinking of selling their devices and consider picking up one used for a cheaper price. (And I encourage those members in that situation to make themselves known to xander.)
For what it's worth, I LOVE my edge and have had a great year with it, and will use it for many more. It's the only thing available RIGHT NOW that will do what you want it to do WELL. But, we're not sure what this company has in store (a new device? closing up shop?) so please do take that into consideration if making a purchase. Any of the regular members of this site (click on Community in the top bar, then click on "posts" to sort by number of posts) would be entirely reliable sellers from which to purchase a used device. Try to make contact with them soon, in case this forum is also a casualty of the website changes.
I can be found around the webz under this user name if anyone needs to contact me again. You know, just in case.