Only high-end milsim gun out there; very fast, smooth & accurate
None really. Slight issues would be cost and weight.
I really like milsim-style guns but I was tired of having to deal with products that could not deliver 100%. I had a couple of Tippmanns and a TM-7 and they were rather mediocre and built with cheap parts. The only gun that got it right was the SP-1 but even it had some shortcomings. So I got a deal on an M-Tac and I decided to try it. So far I love that gun.
The gun is basically a Marq/Victory in milsim form. So you get the same performance. As it might be expected, the gun is very accurate, consistent and can handle brittle paint. It's a steady machine that can lay down ropes after ropes. The M-tac is also very fast, although personally 15bps is enough for me. What is really striking is the level of quality and workmanship that went into that gun. The M-Tac is all metal, save for the front handle which feels very solid.
I really like the fact that you can easily access the bolt, the breach area, the detent (yes singular as in one detent) and the eyes. Maintenance is very fast and easy. Basically you remove two screws out of the body and you can pull out the bolt assembly. You can also easily remove the feedneck and gain easy access to the breach. The feedneck is absolutely unbreakable by the way. The gun so far has been very reliable.
My favorite feature is the cocking handle which actually serves as the on/off switch. On my other guns I never liked to have to fumble around with gloved fingers trying to turn the gun on before a game. With the handle I just need to yank it back to the gun on or off, or to turn the eyes on or off. That is an amazing feature.
Now it has been said that the M-Tac is very heavy and I would say that is relative. To a speedball player if you put the M-Tac next to a Ego 10 of course the M-Tac will feel like a ton of bricks. But compared to milsim guns with tons of junk on it like Tippmanns or BTs the weight is actually decent. I'm a big guy so I don't mind carrying that around all day long, but I could honestly understand why some players might find it unwieldy.
The only minor gripe I had with the M-Tac is that before I had the Supercharger kit installed the vibration from shooting caused some of the screws to unfasten. I solved the issue by securing them with blue Loctite.
The M-Tac is a poppet valve gun yet it shoots and even feels more like a spool. I didn't expect the Supercharger kit to make much of a difference but it actually does. That, and due to the weight of the gun there is absolutely no kick and the shots feel extra smooth.
The M-Tac is expensive and frankly it does not shoot better than my SP-1 which costs a fraction of the M-Tac, but the high price tag is justified by several factors: the gun is entirely made in the USA, the quality and finish are top notch and it is not made in huge quantities.
If you have the $$$ and want the best of the best in the milsim market, get the M-Tac.