Do you boost your Mark V?

I've been going back and forth about whether the best metal rhythm tones on channel three can be found by dialing in a rock sound and then boosting, or removing the boost and raising the gain and treble to obtain the same saturation.

I used to be in the camp of "the Mark V doesnt need a boost" until I saw what a good boost like the Precision Drive can do in terms of increased attack and saturation.

One advantage of boosting is that you can have a rock sound and a metal sound dialed in on the same channel, adding to the already phenomenal versatility of the amp.

An advantage of not boosting is that you can have a more "natural" tone and of course less power supplies to plug in.

So which do you do? Do you boost for your metal rhythm tone? Why or why not.

I do it. I play heavy stuff and I use channel 3 for rhythm parts and channel 2 is actually my lead sound; in order to achieve the gain needed I have MI Audio boost ‘n buff in front of the amp. I’ve tried several other boost pedals but only this one seems to work for me (and the amp). I find the channel 2 boosted far better than channel 3 as lead sound and with proper settings mark V becones de facto a four channel amp

Not so much a boost, but I've had great results running a fuzz into channel 1. Channel 2, Mark 1 mode is crying out for an overdrive. It's so bass heavy. Introducing some highs and mids could yield some interesting tones.

I boost or fuzz over ch1 and ch2 as and when required. Not on ch3 though. But then I run EMG's at 18v though.

Exactly. Pickups, body construction, action, strings and also how you play etc can all factor.
Can be a need that varies from axe to axe.

The EMGs vs some low output beast with pickup to string height set high is gonna be a different result.

I use an Xotic EP Booster and/or a Tumnus, depending on the situation. They both work incredibly well with the amp

I tried playing around with a tube screamer and a TC mini spark boost, and it didn't really do anything for me. I've always felt I have what I need just using the Mark V. So now all I use is a tuner and a Bud wah.