What follows is the opinion of a pilot rather than a controller (as my 18 hours of S1 Ground in ZDC, now outdated over two years, pretty much might as well count as 0 time controlling).
When an ARTCC is split among multiple controllers, it is FAR preferable when the controllers in question use their callsigns to give SOME indication of who covers what. Yes, in many cases I will inevitably still call the wrong one; but with two sector numbers, that's essentially a 50/50 chance, where with a geographic hint at least that chance of a correct initial contact might increase to 75%.
That's a way over estimate on the correct initial contact. Again, my example of HOU_E for HOU_W 87 or 78. You have a 50% chance of guessing the correct one. Outside of events, there is rarely more than 1 center on anyway, so whether or not they use a sector number of name is a moot point.
Daniel, you keep countering with individual instances of pilots calling the incorrect frequencies. You are correct that no system will prevent all such instances, real-world or VATSIM. What I think you may be missing is that when taken across ALL VATSIM instances in which ARTCC sectors are split, helping SOME pilots "guess correctly" will help reduce unnecessary radio traffic to SOME degree. I feel as though your arguments against it are very all-or-nothing. Since ARTCC sectors are more often split on VATSIM during high-traffic events, any effort to help increase an individual pilot's chance to guess the correct initial frequency will be multiplied by the number of pilots participating in the event.
Helping pilots "guess correctly" doesn't change whether whether they use numbers or letters. My arguments are for standardization. Use sector IDs so that neighboring facilities can learn what is where, or don't. When you constantly change between compass rose or sector IDs, you make things confusing for pilots who frequently fly the area and for your neighbors. But using "EL" vs 87 don't really describe anything.
Of course, the better solution would be to ensure that all Center controllers covering only a partial ARTCC area have something helpful listed in their controller ATIS block. My how we dream... ;-)
Controller info is the place for it, as are contact mes during splits... and information on the website. If VATSIM won't allow frequency bandboxing, then we're stuck in this situation regardless of which solution is implemented. Having experience with sectorization as well as compass rose points, nothing beats the ability to customize the airspace with sectorization... nothing. We fly using realistic routings, departure procedures, etc. but then have some wanting to ignore the very structure of ATC that the routings were designed for. Departure procedures are handled by certain sectors for a specific reason. During events, the ability to open the departure sector is second to none. With Compass Rose, that's not really possible without mixing and matching (HOU_E_CTR HOU_11_CTR, HOU_W_CTR. .. what?)
This is why every facility has a website, why controller clients have controller info boxes, and every controller client has contact me functionality .. to help pilots get to the correct controller without having to guess without any information.
