I have recently acquired an aimpoint comp m5 and 3x-c. The comp didn't come with a mount and I'm trying to decide between the two. I plan on shooting this passively every now and then with my pvs-14 so does the extra height of the fast make a huge difference over a 1.93 mount?

How is the fast for normal shooting? Still able to get a cheek weld? I have a piggybacked rmr on an acog and that is pretty close to a chin weld for me but I like the added capability. Is it taller or shorter than that setup?

FAST places the optical centerline 2.26" above the rail.  It is well shorter than the piggyback RMR on an ACOG.  A lot of guys jump the gun and say tall mounts like FAST are too high because they see other uninformed dudes make the same assumptions on Instagram.  But there is a reason that SOF units have used risers like ours, Wilcox, ADM, KAC, (hell - we used to put optics on top of carry handles, on top of M4's 20 years ago).

When you actually get behind a tall mount, you realize that it is still a cheek weld and that the 1/4" difference between it and a 1.93 is not noticeable.

The teacher has spoken! FAST it is then. Thanks for the explanation!

It just needs to be tall enough - for you. Your physical makeup will dictate. I've got an Aero Precision SPR mount on a 0.5" riser, putting the OCL at exactly 2", and it works great through NODs. Maybe 1.93 wouldn't, but 7/100ths shouldn't matter that much. What's the price difference between the two?

There are a couple other things to consider as well. A FAST mount allows you to use standard AR irons in conjunction with the red dot (through the mount) and even includes buis inside the mount if you want to use those.

1.93" red dot mounts aren't going to let you use your AR buis, unless you go to a shorter HK-height set or put your buis on risers.

obviously offset buis would work with either one.

Another thing is alignment with a magnifier. Unity has a FAST mag mount that lines up with their red dot mount or eotech riser, but I'm not sure what you'd use to get alignment with a 1.93" mount other than scalarworks' mount. You typically can't just throw a standard magnifier on a riser and get appropriate alignment. So depending on what you want to do and what other optics you have, that might be something to consider. The FAST magnifier mount allows the magnifier to be stowed in line with the gun, instead of hanging off the side, which was a huge selling point for me.

As soon as I can find them in stock or someone sells me theirs I'll be going the FAST route. The iron sight through the mount is also nice. I was mostly nervous that it'd be too tall for everyday shooting and be heated more towards passive. Once Chip confirmed it was shorter than my piggybacked rmr all concern was dropped.

After writing my comment yesterday I realized I've been waiting for a scalarworks 1.93 to pop up in the ee but I already have 2 FAST mounts so it would make more sense to get another one of those.

Optics planet had a few tan ones in stock so I ordered with a 10% off coupon. Got an email later saying it is shipping soon. They typically ship one or two days after sending the "shipping soon" email in my experience.

Ended up getting one from optics planet this morning. Thanks for the heads up! Now to find a magnifier mount.