You can (and probably should) regard BB10 and OS7 devices as being from different companies. Stack them up against iPhone, Android, WP and what ever else is out there. Then go with what works best for you (hmm have a seen that before?).
I made a suggestion during the run up to OS release that RIM (now BB) move away from carrier provisioned BIS. Essentially build and provision BB10 the way they have, then market BIS access as a subscription service through BB World. (The first indications were that while the developer devices did not need BlackBerry data plans the Z/Q10 would, they obviously changed their minds.) My suggestion seemed well received but could not be implemented by release time and would be sent into the idea grinder to see what the company thought. So who know, maybe there will be a point in the future where you'll be able to choose to have BIS service or not. I happen to like the way they have set up the Z10. There are things I miss (the ability to edit the APN, BBM Music [yes I was the other person using it], push email that allowed me to get email from my ISP which is still using bear skins and stone knives. I could get all of that back by putting my Z10 back in the box, giving up my PAYG account in favor of a much more expensive BB data plan that includes a hockey sock full of voice minutes I'll never use; and go back to the 9810. That isn't going to happen. For me the Z10 is a much better phone and a much better value than any of the other options, including BB OS 7. Would I like to keep the Z10 and cherry pick the old features I want to bring forward? Sure would. I can, have and will continue to tell BlackBerry what I would like to see, but they're not going to do it just for me. Of all the moaning I've read on forums about how bad it is to live without BIS there is something missing. I haven't seen too much of it where it would do some good, in the official channels BlackBerry has set up for people to report bugs and make suggestions; where others can comment and vote for there importance. If people really do want to see BIS back for BB10, and want to pay for it, there are venues for making that message clear.
For those who may be interested in making suggestions and constructive criticism go to this link:
https://www.blackberry.com/jira/secure/Dashboard.jspa you may have to create an account.