I think it all rolls back to SQL so I would not think it would be an issue until your DB started to cough at a huge query but I do not see that ever happenning unless you DB box is oversubscribed.
I have a similar alert for 1 set of apps and right now I think I have close to 10 listed.
Yes...all alerts boil down to is a SQL query. You can see them in the AlertDefinitions table (I think...it's something like that).
Either way, we've got an alert just like that. It currently has 6 componentNames it is looking for - under the ANY qualifier.
How many are you looking to alert on?
We're not a huge shop so we don't have bunches and bunches of them. But we frequently have had APM templates setup for ONE machines apps (several components.. some may be HTTP most will be SNMP processes) and then have a alert tied to that single machine and its apps. What I would like to do is grab 10 or so app monitors for different systems and assign them to one alert so if any goes down we get the alert with the information.
basically the alert may have 10 dofferent apps it is monitoring, each with 4-10 compnenets. I was just worried about taxing the server.