Might be worth it depending on cost.
If it takes say $100 a year extra to not get ads it wouldn't be worth it for me (unless the number of ads for those who don't pay increase but that would then be reason enough to leave).

Of course without an alternative to PP donations are for many (including me) a pure hypothesis, so you might want to consider adding creditcard transations alongside PP which I think would get you quite a few more donations than offering an adfree alternative.

I dont' think that there should be a compulsory subscription, although an ad-free incentive does sound appealing, although I'm not too sure how well it'd be taken up.
Too many people are like me I fear, accustomed to the freedom of the internet and the free services it provides. Any site that forces subscriptions quickly sees the close button on my browser.
I know that costs are a turd, we all have to pay to breathe after all, but one of the things that endeared me to this community was the absence of any pressure to "sign up now". I don't mind the ads, and if circumstances permit I would donate out of respect more than anything else, but ads-free would make a nice bonus if I did.

After listening to you guys, I have reduced the price of a sponsorship in half! (Existing subscribers have had their subscriptions extended to reflect this)

naah.. you gotta make your bucks. If te ads werent there id really feel bad about
being a slug and not coughing up those 20 viente white mochas..

although i had a thought occur to me.. this is rare but sometimes.. just sometimes it happens; i think. the thought was-->
http://www.daniweb.com/techtalkforums/thread14438.html

my apologies.. the cost is now less than 10 viente white mochas.. annually
or one a month.

It used to be $10/month and I lowered the price to $5/month.

right on. you might peel me for some loot yet.

That would be very appreciated! I guess $5 is more reasonable than $10.

I just joined a few days ago and have been really enjoying your site. I delayed subscribing only to be sure this was a site I would continue to return to. I'm glad I waited. I just left Pay Pal and have subscibed for a year. It's well worth the value. This site is a wealth of information and I'm proud to be a part of it. Keep up the good work!