The difference is there, but it's probably more on the order of $100-$150 or so, haven't looked at the iSuppli reports. But due to the service fees tied to cellular devices, they tend to bump the price up and hide it in the contracts they lock you into. End result is everyone does, and you end up with a market that will (somehow) tolerate $550+ devices from Nokia (device uniqueness not withstanding.)

I would not buy a WiFi - only tablet, because I'd have to carry a
cell phone too.

For 'retail price' of cellular radio, just look at iPads. The difference is exactly $130 between the wifi-only and wifi+3G models. And these don't come with contracts/operator subsidized/encumbered costs.

Opinions?

For your "safety and security" no

I've seen some stuff on BBC few days ago, that US Cyber Defense Department is already targeting more and more powerful devices they realized loosing control on it.

They will give us many reasons if we can't find any

The ubiquity factor is very place-dependend. For example, it took me a trip to Finland to realize how ubiquous WiFi can be and why it was completely logical from that viewpoint to omit gsm. I was on a N810, had 5 APs in range even in the middle of parks, and AP aggregation meant I was online almost continuosly. Adding SkypeIn/Out to the mix made it complete and I did not miss expensive gsm roaming one bit.

As far as security is concerned, isn't there more risk on public wifi where other users can scan, intercept, setup honeypots, etc?

At least the operators are clear legal entities that can be easily identified and acted upon if there are issues.

Depends on what you mean by "public," if it's encrypted then you're limited to the security at the end-point, otherwise you're open to anyone that has airsnort or wireshark.

At the very least, you won't mistakenly connect to a 3G connection that will proxy you to goatse

N900 needs 3G to be a truly mobile device - you can't get WiFi in the car, on the bus, train etc (OK some trains do now, but generally speaking not).

Also, away from the suburbs there's no WiFi. I would say when not at home or the office, I would use 3G 80% of the time and wifi 20%.

thanks: mastac
Apart from paying for a chip that has the extra radios, you don't need to use the sim card slot. Just think of it like a spare PCI slot in your PC, there if you want it and only wifi if you don't use it.

@wmarone: I think the security issue is more sensitive for the general public which don't share as much concern or effort to enhance their online security profile as most of us here. But we're still more open (to attacks) on a public wifi from 'fellow users' than on cellular data connection. Moreover, unless you use encrypted tunnel to your own proxy/shell for all your communication, then you'll still be leaking info (browsing, im, etc).

Ps: I'm glad I've never been mistakenly lead to goatse, unless it's by my own accord.