The player collision with grid holes still feels wrong. I don't know if this has changed with the convex hull code but try driving as close as you can to the edge of the hole. It seems to be too far away from the edge to me.
The player's tank is modeled as a circle. Other things he can run into such as holes, buildings and enemy tanks are now convex hulls (they were circles too). It sounds like you'd prefer to see the player's tank be modeled as a convex hull as well. I'll put it on the list.
Are you collecting stats from the client? Things that would be potentially interesting to collect, every tick:
Number of enemies on screen
Number of bullets on screen
Current zoom level
Which control scheme
Number of gridshards saved up
You can then go back through those logs and plot distributions and also find correlations by using sploms — a really quick way to see if there are potential correlations. (I can help write the visualization code)
I don't know how big your packets are right now but it seems like a relatively small amount of data. If 5 times per second is too much, do it less frequently. :-)
I'm looking back on RotMG and pondering the kinds of questions I'd like to answer (with data) in Grid 12:
Do people use the same control scheme all the time or do they switch depending on where they are? (I suppose we'd need to record location for this**)
How many grid shards do people collect before either dying or going back to town? Is it consistent per player (e.g. is it based on your personality)?
Are graphical slowdowns caused by number of enemies, number of players, number of bullets, zoom level, or none of these? Do they typically occur in certain areas?
How “safe” are you when playing? Do you retreat when you're at half health, or do you wait until the very last minute? I'd imagine this is personality driven too. It'd be interesting to compare this to deaths.
Do people use the same zoom level all the time, or do they switch a lot? Do they use some zoom levels during combat and others in town?
I'm sure there are other questions we'd like to answer. Some of this you'll get through anecdotes and user testing, but it's useful to collect data on a large scale too, especially if it's cheap to do so.
** If you also record x,y then we can build a graphical “heat map” showing the values of each of these variables in every place on the map. Not sure how useful this is, but Halo did some cool things with the data, and we'll only know if we actually collect it. Events like deaths and leveling up would be interesting to map too.