When I did it before, I did not do a mashout and the beer seemed to turn out fine, so I have no problems with that. Feel free to chime in on that Barc.
What I like to do is this:
1 Mash for 60-90 min with X water temp.
2 Vorlauf and do a complete drain of the tun.
3 Add in half of the sparge water @ 180-185
4 Stir mash, allow to sit for 10 mins.
5 Repeat steps 2 - 5 vorlaufing before doing the drain.
This typically nets nearly 75% efficiency with a 60-90 minute mash. If we do a 90 minute mash and do a good sparge, we should be OK. It doesn't have a true mash-out but it does get most of the sugars out. And I haven't had a problem with tannins or off flavors doing it.