Ok, in my MJ I ran 3.55s with 35s for about two and a half months. I know that's not the same as 33s, but bear with me. After that, I had 4.88s for another month and a half. Then I was in a stock XJ for about 5 weeks. Now I'm in an XJ with 35s and 3.55s.
35s and 3.55s the first time around kinda sucked, and I knew it had been better stock, but it was ok. I wheeled it once in the snow and I didn't have a very good time. I was in 4L basically the whole time, even places I knew I could have done stock in 4H.
I got my 4.88s and was really happy. Again, one snow run, but it was great. That and the spool, and I was having a lot of fun. Even though, looking back, my 4.0L was pretty sick (and gave up that night).
Going from 4.88/35 to stock/stock, I didn't feel a very big difference.
Now I'm 3.55/35 again, and maybe because it's just a healthier engine, it doesn't feel too bad. I just keep it in 3 most of the time. Still, I know it's not doing good things for my drivetrain, and I'm looking forward to salvaging my 4.88s and being geared again.
So you can run big tires on stock gears - and in fact if you're thinking about it, I bet you will - but you will really like it when you regear. And you should regear about as soon as it becomes an option, even if you can't do both ends at the same time.