See? I knew I was going to cause friction. I estimate tight is tight enough to not fall out of the board when I invert it to dust it out, or to pop out when I dust it, or to develop cracks in the stem holding it to the switch. Sideways flex I only notice when playing games (in the WASD cluster, or any other switch that is held down when playing).
I can't speak to the tinny noise at the moment - also I am a firm nonbeliever in "ping" or "ring" or any other annoyance at keyboard sound. I do agree about the nubs.
Just remember, I am not an expert, your mileage may vary, this is all anecdote, my experience should be weighed against the majority, Elite Keyboards is an excellent company, I plan to spend more money there in the future.
Also, when are the new FC700s arriving? 
Haha, you're not causing friction at all. I'm just always trying to put my finger on what criteria are most important to customers. If keycaps are popping off easily or cracking, then they are defective. The mounts on Leo caps are designed a little looser than Costar, but we're talking fractions of a millimeter that only change the force required to remove the keycap. So neither keycap type will shift or lean off the keystem before the keystem itself starts to skew inside the switch housing. If a keycap is popping off or has cracked mounts, they're either defective or damaged.
I think the "flex" you speak of isn't really happening. In addition to the mount-keystem friction, the cross shaped keystem design of Cherry MX mounts won't allow mount-tilt in any direction unless the mount is horribly cracked or the entire internal length of the mount is over-sized to the point of zero friction (and even then...). This is one of the reasons why the Cherry stem has stood the test of time while so many other keystem designs have come and gone. My best guess is that the sharper edges of Costar keycaps create a greater perception of hardness when you're pressing the keys rapidly because the keycap edge would be more apparent with less applied force; I.E. the same quantitative "perception" of the keycap digging into your finger for the Costar might be at 35cN of force whereas with Leopold it might be at 38cN. More force means the keystem could skew or lean more inside the switch casing, but the keycap mount itself isn't moving. (This, and the addition of that nasty coating, is one of the reasons I attribute to some people's opinions that FILCOs "feel" solider than other keyboards; a manifestation of their perception rather than actual material or build quality.) Whether we realize it or not, our fingertips can recognize surface variation as little as 0.001mm; but those same nerve endings do adjust to change over time, so the next thing you know, someone will opine that the softer edges on the Leopold caps are more comfortable to type on for long periods of time. So, I can't say which keycap is a superior design, but I won't say that fractions of a millimeter don't matter. They do.
No plans for the FC700s at this time, but thanks for your support!
