To answer your question about different services I'll make a few quick notes about some and give my recommendation...
iDev - Elizabeth is right about the tedious fixes that need to take place with it ... it's not a bad affiliate program for starting up, but isn't very versatile when you get going. I've lost hours and hours of sleep over it and it's delayed a few of my launches (so that's not my top recommendation LOL)...
Ultimate Affiliate is one that I have set up with my company and have used once with no complaints. The only reason it's not my main solution right now is because it is very basic and very outdated... but it definitely gets the job done and makes it easier from an affiliate managers standpoint than some :-)
JV Manager - I love some of the stuff John Delavera comes out with and haven't heard many complaints about JV Manager... I haven't used it yet so I'm going to let you talk about this one Mike, but I don't have complaints about it...
Now my current system (because it was easiest for me at the time) is 1shoppingcart... the main problem I have with it is chargebacks with affiliate commissions ... I've had issues when an affiliate gets a sale and then that person refunds (sometimes my affiliates still get their commission)... other than that it's fairly simple and a great friend of mine who all of you know uses it with his affiliate program of 30,000 people -- so it's robust enough to handle a lot of growth...
Another downside of 1shoppingcart is their email client is horrible ... so you need to export your lists to send emails (but you should do this with most programs anyways)...
That's my two cents ... I'd love to hear your opinion on this Mike!