I also have both versions of the cyclone. I haven't modified the juice hole on any of them and they work so well just like they are that I haven't had the motivation to lower the juice hole. In fact, with the standard cyclone, I find that I can take twice as many pulls (~7 lung hits) between squonks. I'm starting to appreciate that more than a good drain. I think the juice clouds up a little faster but other than that they work awesome. Of course the AFC setup with dual coils is pretty thirsty - no way I'm lowering the juice hole on that one.
I also noticed the juice hole is a bit lower on the parts I received from the London source. Not just off the base as some would prefer but not far off. There could also be some variance in juice hole height from one atty to the next.
As for drilling air holes in stainless I have found a tapered diamond Dremel bit works awesome. Stainless is hard stuff but I've drilled 7 or 8 caps with one bit and it just keeps going. Its also great for cleaning up the burrs on the inside of the cap after drilling. Also because its tapered, you can incrementally increase the hole size until you find your sweet spot. When I first started experimenting with air hole sizes I ended up punching through at 3/32nds (max taper diameter) and switching to lung hits.
Dremel 7144 Diamond Tapered Point 3 32" Cutting Engraving Carving Finishing Bit | eBay
PS, I would go with the stinger or a standard drip tip. The fusion will increase the chamber size and that will affect flavor. I have both and I found I like the wide open shorty style drip tips on my cyclones.