Should I bring my iPhone?

Take whatever you have, better than letting it sit in storage and be useless. (maybe not whatever you have, but if there is a use for it, take it!)
 
i'd do it. An iPhone would be easy to carry/conceal/protect, and the benefits seem pretty tremendous (I'd kill for Brick Attack on a long siding!!!).

Edit: someone should really write some trainhopping specific iPhone apps. CCG, Rail Atlas, ACTS, scanner, etc...
I'd say no to the CCG - there's a reason those are handed from person to person. Maybe if you had a password but still some tech savvy kid could get it in no time. Just my thoughts