1. I didn't do as much testing as I would have liked to before bringing it to clickbank - fortunately though it was my 30th or so product so it was enough intel for me to confidently move it from paypal buttons to clickbanks setup within 50 or so sales and 4 different sales pages.
From my sig link ::
This was enough to get affiliates going. Once it was on CB we continued split testing and adding to the offer as much as possible as we grew, we plateau'd a few times as well and... actually I have a full case study of my whole journey with this here >
http://www.wickedfire.com/enlightened-members/147755-case-study-versioning-installment-3-a.html - click that and go to my second then first part of the series, I drop a lot of intel of how we handled the split tests and how we integrated our backend, then recurs, then overcame each plateau of growth to set a new bar...
2. I have been at this since 2007, back then I tried CPA, and CPS as an affiliate before making my way into vendor territory - and by then I grew a major fucking hate for the CPA game.
I also consulted a few offers that were being run through a half dozen CPA's in their tests and wanted to convert to CPS and go digital only, which opened my eyes to how fragile the CPA game is. Unless you're a boss already in that game, the advertiser can be fucked easily, so can the aff, so can the network - going in any direction of those three, where as clickbank doesn't have that problem.
And yes, in my 40 or so products to date, I did try the mmo shit in my early days and it's lil' spike money - this is one of the most tricked out clickbank accounts and is not in the mmo niche, and has been a top 100 product (premier/apex) for 2 years now so there's a lot to be said about clickbank being safe for long term whitehat offers (don't let that fool you though, there's tons of shade at CB as well from affiliates to vendors).
Barrier of entry for me, or for CB, is small - $50 to list your product once you figure out your conversion mastered page. I am the designer and audio producer so my costs are minimal - Getting a digital product up can cost you tons or next to nothing depending on what you're doing (ebook vs membership site vs software vs a combo etc.).
Basically - if you launch an offer, and prove it yourself, and document it yourself (i.e. being your own affiliat of your own product, can you be profitable? prove it), and you have good conversion rates, and big margins (who are we kidding - it's digital, cost of reproduction is zero and delivery is instant, YES you can offer 75% commission, and still make millions yourself by making others rich and attract the best aff's due to those big margins), then you will see affiliates flock to you with very little effort in recruitment.
I've seen a good dozen one hit wonders spike through clickbank into top 5 position and die within 6 months and make their millions, and never be able to repeat it again. I see those that do overlaps of pump/dumps by design to maintain big monies for as long as overlap happen, and I've seen a handful do what I've done, create something that lasts for years, withstands the market shifts, big attacks by competitors, being diluted by having many competitors, and still kick fucking ass having more market share than all competitors combined today.
Having your own product rocks IF you can get past that first barrier, creating something extremely attractive for others to make money from.