I am about to measure the drive-time for 50k points (households) to two facilities using 'closest facility'. Before I start, can Arc handle that many points in Closest Facility? When I upload the points as incidents, will it let me upload that many or is there a limit? Will it take a large amount of time? Is there a better way to do this?
Essentially, the two facilities differ in that a householder would prefer to use Facility A over Facility B. I.e. if a householder is up to ten minutes further from A than B, they would still use A. So I'd like to know how many households are up to +10 mins further from Facility A than B.
ArcGIS can handle this. I've done similar analysis with approx. 35,000 incidents. It will probably take 5 to upload the incidents. The analysis will probably take a good 30-60 minutes, depending on the specs of your hardware.
Are you planning to use the online services to do this or using desktop software? There are limits to how many incidents/facilities you can send with one request to ArcGIS online. Desktop does not have these limits.
Also if you only want to know the distance and not the shape of the actual route that was taken then I suggest you use the Origin Destination Cost Matrix solver. It runs faster. So with the OD solver, you will have two origins and 50k destinations. Specify some cutoffs if it makes sense, like do not bother computing of the distance from origin to the destination is more than 30 minutes, etc. The solve will be quick and you will get a table with the distance values that you can further analyze for your needs.