Mast is a pretty good feel to it. At 200 (which is where I started) it increased energy and a tad bit more aggressive (honestly was more like assertive than aggression). Mentally it had me thinking clearly. I dont think mentally you would have anything to worry about unless you're super sensitive to dht. Personally 19nors mess with my head more than anything but they also impact the neurological system on a different level.
Bumped up to 400 after 2 weeks and stayed there and honestly the only sides I got were an increased in blood pressure and I started waking up at like 3-4 am. Ime once the system gets overloaded w a dht you can become "overly energetic" if that makes sense which could include irritability, aggressive behavior etc. However I stopped the mast due to bp and the headaches I was getting along w poorer sleep. Those were my only sides and theyre really minimal w mast compared to other aas. And testosterone for me works great. Even solo if I bump my dose up to 400 I see increased size, strength, libido and overall mood. I'm one of the lucky guys that test just works well for me and I feel great on moderate doses of it.
I think there's a lot of misinformation with masteron and how it actually works at controlling estrogen. It does work slightly but not enough to control estrogen at higher doses of test etc. It also (to my knowledge) isnt capable of crashing estrogen per say. It did help on 200 mg of test e but for me my diet really dictates estrogen problems more than anything. I take about 6mg of exemestane every 2-3 days or so which seems like a tiny dose but its all I need. I think initially the mast helped but after a couple weeks everything leveled out and I added the ai back in the mix w no problems.
I think if you're going to add anything to trt to make it better masteron is the best option next to low dose primo. Mast is a dht so as little as 200/week you'll see some drying, hardening, increased libido, energy and lowered Shbg which will provide more free testosterone. At a low dose the sides are pretty much non existent.