I've only made a few starters so far, but I pitch the whole thing!
Actually, my starters may not be true starters, per se.
For the few 5 gallon batches I've made over the last several months that had a high OG, I basically just smacked the Wyeast pack the day before, pitched it into about a quart of low gravity wort (just some boiled DME and water), put it in a growler with foil over the top and let it run for about 24 hours before pitching into the full batch the next day. Just swirl it up and dump it all in there. Seems to have worked fine so far. The yeast definitely get some work done over those 24 hours as it gets fizzy and smells yeasty.
It's such a low volume that I doubt it changes the beer much, and I figure I'm just adding more of the same (water, malt) to the full batch.
The only times I've needed blow off tubes were after making starters this way (as opposed to just pitching the contents of the smack pack or dry yeast envelope). So it definitely gets them going, I guess.