I find it really interesting that this conversation has often gone down the 'All or Nothing' route.
In an ideal situation it's always a good IEM mix and a nice amp. I'm a massive IEM fan and go ampless where appropriate, but I know I play better with the reaction of an amp and the feeling of (for want of a better word) some weight behind the notes. Stuff like the Woojer and platforms can do the same thing but unless you really want it to be quiet on stage you may as well bring an amp instead. I find even a quiet amp makes a big difference to the feel of the instrument. @Swijn it sounds like you're in the perfect situation to get stuck in with some help. If you're using your Amp DI there's not much pain in bringing a cab... some gigs you may find (as I did the other day) you forget to unmute the cab and manage not to notice!
Also, from the perspective of a working guitarist, I far prefer it when there is a bass amp on stage... I find it encourages a more musical approach.
Short version: Getting used to IEMS gives you a lot of choice in how you approach a gig, and you'll certainly never regret being able to hear better (both and off stage!). Be flexible and appropriate to the situation, experiment and give yourself what you need to play at your best!