Your EVO is performing identically to mine. From what I can gather the cause is the bamboo being slightly too restrictive. My symptoms are unevenly vaped bowls, depending on how full (identical load size at any temp vapes fully and evenly with no stir in my OG) and the restriction of the draw keeps my waterpieces from being used to their full potential. With my OG, I could stack bubbles to the top of my GBD FC showerhead bubbler, and my HydraCirc perc fired fully and freely...this is not the case with my EVO at all. Even using the dry mouthpiece, the restriction is un-desirably strong. With one waterpiece, the restriction makes me feel like I'm about to drool
All of that being said, I am still mainly using the EVO vs the OG, as it heats up quicker, and is cooler to the touch by far, on the lower half of the unit. Also, the brighter LEDs, removable cord and lightweight build make for more convenience. Still, I find myself unable to shelf the OG, as the EVO just doesn't satisfy in the ease of use department when it comes to draw restriction. I love love love the thing, don't get me wrong, but I can't really seem to enjoy the draw speed of the EVO, or tolerate it when I am trying to medicate quickly.
That being said, I messaged SM back when I came to the conclusion that it was too restrictive for me, and potentially too restrictive in general. I didn't want to come across like I was saying it was defective or anything, but I do seriously believe it is out of spec. I feel these things should be brought to their attention so they can focus on preventing the issue. I requested to send my unit in once they have caught up on IGG orders/pre-orders, and are stable, etc. for "repair," stating that I would like the bamboo to be replaced with one that is less restrictive that what is currently installed; if possible, as close to the OG as possible in terms of restriction.
So, I am sure for some or many users, this wouldn't be an issues. I know that the Cloud + is known to have a more restricted draw than the OG, and the EVO even more so, but I don't believe it should be as restricted as it is in my unit, or as others seem to be experiencing. Otherwise, I'm still loving this thing, and I will miss it when it goes away for it's little upgrade...but the OG will keep me more than content in the meantime...as it's doing right now hahahah