Threading is more like writing the code in your head, then fueling it into a usable CF is why theirs Fade damage, that's why you can alter how good your final CF is.
As for Chrona's Threading, I think you've both forgot some rules - a penalty of -2 to subsequent attempts at the same test. I think that applies to Threading as well as Spellcasting...
Can you also quote somewhere for this?
P.S. Matrix and Magic are completely different, bad things lie beyond comparing their rule sets, if Technomancers were to be treated like Matrix Mages the rules would be worded the same. Drain is the strain from Mana Weaving, but as far as I can tell Fading is like it sounds, your consciousness fading away into cyberspace from becoming too far removed from reality and the adverse effect your body reacts to this with as it tries to keep you in your meat.
For me threading is more like coding in your head and then broadcasting it into Matrix as complex forms. Complex forms you have are just the programs you have memorised, that you're able to rewrite and broadcast easily.
When you try to code an algorithm you are just tiring, your brain cease to receive and send out the signals. When you fade your Matrix imprint fade out, not that you fade into Resonance. The brain fatigue is reflected as stun damage, and overload (like when coding high rating forms can damage it physically).
I have my own set of problems with matrix rules as well, for example I definitely don't like sprites. For me this are just programs or rather agents, and I see no reasons for tasks owning, or eight hours limits. I also don't buy those mysterious inifnite resources they're running on.
but enough ranting, you haven't aneswered on my question on how are you going to pass the guards, and I've decided to bump the action a little further before it stall completely.