They have pretty heavy handed moderation (like facepunches for going a little off topic or not posting in the right forum).
That said, delurking and popping in a referral link in your first post looks exactly like spam and is probably a poor way to introduce yourself to that forum (or any forum, really).
I'm only an occasional lurker there, but it's still a very solid forum with excellent resources.
As for the $100 vs $300 referral links, I'd feel pretty shitty if I sent any of my friends or associates to a crappier link instead of giving them the extra $200 discount. As an example, I have a link to some credit cards with bonus offers on my personal blog. If I know I have a credit card that gives 25,000 points/miles for signing up but I know there's a link for 50,000 miles somewhere else, I'll try to suggest readers google and find the 50k offer (or go to flyertalk's master thread and find it or whatever). No reason to short other people $200 or 25000 miles just to make a buck yourself (unless you're in it for the money!). Or alternately, if there's a 50k offer that pops up a few times per year (like Southwest Chase card) instead of 25k at most times, I'll advise waiting to get the bigger bonus when it's offered.
Edit to add: somewhere on the margins I might recommend a slightly inferior offer if the net between what you and I receive is better than the straight terms of the offer. Like if MMM's sofi link was $125 bonus for the refinancer but my own link was $100 for me and $100 for you, I might give my own referral link to a friend since together we net $200 (at the expense of costing my friend $25). There's a rationalization for my slight sleaziness somewhere in the utilitarian field of ethics but I don't care enough to elaborate right now. :)