i'd say do it... i had the same debate.. i went from 1.1.3 to 2.1 about a month ago...
the little things i noticed was load time when u turn it on/off.. but thats not really that bad at all.. almost every app i had, i have again..plus 600 more.. its a month later & i'm still going thru apps.. i haven't even been on cydia. only to DL catorgoies cuz i had so many apps i ran outta pages lol.. its outta hand i got so many apps i dunno what to do with them apps LOL

.. i'd say do it. i did, i'm very happy..
how to go from 1.1.3 to 2.1:
1)i restored to 1.1.3, then rejailbroke & unlocked, then upgraded to 2.1..(just cuz i live in canada i'm not with AT&T)
2)then i restored to 2.1.
3)now find quickpwn & the 2 Bootloaders & a copy of 2.1 1G frimware... trying watch a video on youtube if your unsure... u could probly find a link for everything u need there aswhile..
$) its pretty simple from there.. quickpwn step by step......... your good happy modding