I agree if you are terrified that there are scammers after you, then don't ever use wifi. Hmmm I would never do things such as banking over public wifi but browsing the internet....yep sure do.
Yes you are right, at least with Verizon you can pay the $30 monthly fee whenever you want to use the 3G. Still you have to pay the $130 price for the 3G iPad and then whatever the cost is whenever you decide to use 3G.
When I want to use my ipad using my phones 3G, I just use one of the many free tethering programs. I have only been in a situation once, while on the road that I needed to do that.
Bottom line, the choice will ultimately depend on what a particular person finds meets their needs. Some of us use our ipads for different uses. I have a couple desktops and a laptop for serious use. I use my ipad2 strictly for convenience.
I respect everyone's choices.
If you use public wifi, even paid wifi at hotels and such, be aware that you don't control security and you have no idea who has access to your data. There are even some scammers who set up free wifi networks and wait for unsuspecting people to log on. Google for something like "public wifi risks" and you can decide whether you want to risk your email accounts, social network accounts, financial info, etc., depending on what you use your iPad to do.
For me, 30 bucks a month is a better choice than public wifi any day. If I couldn't afford it, I'd still avoid public wifi.
By the way, there's no subscription required for 3G. Pay only when you use it, by the month or till you use your data limit.