I've done both the ejection port mod and the gas tube mod, and find them quite effective and well worth the effort.
I hand load and I get mad if I waste too much time crawling around looking for brass, so I drilled the extra gas tube port holes much bigger than I would normally suggest if you want to keep the covered-in-mud-reliability of the SKS. My brass ejects at 2 o clock and ends up in small area about 5' away from me just forward of the muzzle. The ejection pattern stays consistent, even with the last batch of hand-loads which were starting loads of 22 gr Reloader 7 behind 150 gr v-max (.308), which is quite light compared to any surplus or commercial loads. Just make sure you start off small on the hole sizes in the gas tube and you should be fine. I have a really bad youtube video (Bubba SKS) up that shows the position of the gas tube holes on the finished product.
I regard the ejection port mod as a must do on any shooter grade SKS; I hate shell deflectors almost as much as I hate the ejected casings hitting the awning above me, and in malicious defiance of the laws of physics, pelting back at me with good reliability.
