We currently offer bigger sized avatars to our members if they have a paid susbcription, we'd really like to keep that ability if we were to switch/upgrade to XF. I know this isn't currently possible, but I would like to make the suggestion that it is added as an option so that Admins can choose what size avatars different groups can have or if they want them to all be the same size.
See I'd have to disagree what it'll look strange, as long as you keep the sizes within reason of each other, ie not have them go from 50px x 50px to 200px x 200px it'll look fine.
Our current vb board uses different sizes per usergroup and there is no issue with extra space in the postbit at all.
The layout of xf is not that different postbit wise to most other solutions which allow variable sized avatars based on permissions and I think it will be beneficial to offer it as an option and then allow the forums Admin to make the descision as to whether or not they want to use it. otherwise the postbit of all xf boards will look very similar if there is no control allowed over avatar dimensions
I don't think it would necessarily look strange if you allowed a different avatar dimension... This is my current avatar on our vb board:
Having a longer (portrait rather than landscape) av like that, wouldn't make things look strange. We have it set up so that admin have larger avatars like mine (same size and shape) whereas regular members have smaller ones, which they can't alter - they are fixed to be a square and smaller. It makes it easier for members to instantly recognise who is staff and who is not. It is something we've found really useful and would be good if we could continue doing so with xf. I do agree though that it would look really odd if we had avs that were rotated to be landscape or random sizes compared to everyone else's... but if there was some way to make it so there could be a distinction in sizes even if it was restricted so you don't get some bizarre stuff going on.
As it is, there's not much difference between staff and regular members and that's something we'd really miss. Particularly since that's one of the only 'perks' on our forum of being on staff.