It's not an issue right now. But
if when there are lots more people here, and you all have dancing superheroes etc. then there will be a problem. I'd rather try and contain it now
The main objection to [img] tags isn't that they use bandwidth, it's that they use the bandwidth from two sites - the original and the place you are looking. Everytime someone inserts one of those external smileys, for instance, this system has to go to that site, find the file and copy it here (which is why they sometimes disappear because the link has gone.) And it's actually a little bit more than that since the messages also have to be sent between the systems in the first place.
So at some point I will take down the original helicopter picture that Redjimmy uploaded (or ask him to), because it's 350k. Every time 3 people open the thread, that's 1mb. According to my webstats, there were about twice as many "hits" on the site on Monday as there were on Tuesday and yet the total data transfer was quite similar. And that's probably mostly due to a large picture and some dancing rabbits/cats/giraffes/penguins/whatever, that mostly all turned up today.
As I said, it isn't an issue right now; we have got lots of spare capacity. I just thought I'd mention it...