Well I can't speak to other events other than Irene that I just went to along with local events. But I went into Irene well probably over prepared mostly since it was a long trip and I didn't want to have issues. For myself my focus if/when I do it again would be less on guns, I spent allot of time and energy on my gun, and backup guns etc. To make sure I wouldn't have any issues and I also brought backup guns for the guys who went with me. So I focused allot of time tuning and working on those guns. Then I only shot a couple thousand rounds, which is less than I typically would in a weekend pickup game;) So I didn't need to worry about reliability nearly as much that's not much wear and tear, and to be blunt there weren't allot of guns there shooting that well(in the guys I was with etc).
I was actually fairly surprised that I saw allot of guys with fairly substandard working guns, IE hopup problems etc and not issues necessarily that just cropped up. More this is how my gun shoots type of issues, and often these were guys wearing allot of fairly expensive by my view gear. So I sort of took the opposite approach, I wear pretty inexpensive gear, functional but nothing fancy so long as it works. But I put allot of time into my guns, trying to maximize accuracy and range. I guess my point would be that depending on how much you fiddle with internals most guys I saw at Lion Claws don't spend a ton of time tweaking their guns, mostly show up and play type of deal. I should note I'm sure some guys there did indeed spend allot of time and money making their guns function perfectly etc, but I generally didn't see those guys when I was playing, the majority of the time I was hearing about issues with their guns.
The other suggestion would be make sure what kind of specific gear you need for their game. In the case of Lion Claws I needed a dead light, since we don't play at night that was new to me. And I'm drawing a blank now but there were quite a few other small things I typically don't need/use that I had to get for that game to make sure I was following their rules. That said I also saw a fair number of guys who didn't have that equipment and no one said a thing. So if it were a Lion Claws event I'd be less concerned with being perfectly compliant just get close and likely you're fine. For other hosts etc, best to contact them and see if they have a list of required equipment available.
And so going back so long as the gun is functional and works properly and has at least a mild tune on it, you're likely ahead of most of the guys I saw at Irene. But that's my limited experience and view;)
And I should say honestly my local games seem more competitive as far as guns go, could be because we're smaller group and there is a fair amount of tech knowledge. But here typically you've gotta have fairly decent equipment to keep ahead of what others are running.
Luke