iPad 4th, wifi or wifi+4g ?

Hi,
I hope it is the right place for this question.
I have an iPhone 4s which I can use for tethering, so my question is:
should I buy the WIFI version to save money sharing the same data contract? Is someone already had this experience? ..just to know if enabling an hotspot on 4s each time I need to use the internet connection outside a wifi lan is very uncomfortable or not..

Thanks in advance
Fabio

Thanks guys! I bought a very cheap refurbished iPad 2 16 GB Wifi and I confirm what you said! tethering works very well but very shocked from the terrible battery behavior..how is it possible that this feature keep so many energy??!! I calculated more and less 50 % of my 4s battery for one hour of tethering (maybe worse!)..
But if I consider I have wifi at work, at home, in hotels..and considering that abroad, because of expensive data roaming, I cannot use 3g/4g, I think that for the few times I need to check newspapers or emails or maps, I can definitively tether..
Now that I connected all points, i am thinking to go to an apple store and exchange this new ipad (got 3 days ago) to the 4th generation 64GB only wifi..hope this will be possible!