I think Summoners are fine.

[Solen]

I only need 1/4 of my DoTs to crit for the tick every 3s to hit for ~380-390. That's without miasma II. RS I was seeing crits of 500-510~. This is without Relic+1.

It is sustainable with a BRD.

And your crit rate is gonna be somewhere around 11 to 12 percent. As I mentioned, you are gonna need miasma 2 and a crit just to hit 400 per tick. No one here, even with a relic +1, is going to be averaging 400 per tick unbuffed without outside influence.