If running with a group appeals to you, it might be nice. You might get some interesting feedback too, on what is a good idea and what is not when different places hurt.

Do they 'run' or 'jog', and what about you? I used to say I went running but I mostly used to jog. I know other people who 'run' though.... and they really run.

So then, it partly depends on the pace that you keep when you practice in the gym and whether it at least matches theirs. (OMG do I need to get used to writing practise again? ) I'd have to look back, but you do more than 3 miles in the gym, right? So distance wise you should be covered at least.