Pilsner Urquell has always bee made at a simmer, but for 120 minutes.
Brewing is full of tradeoffs there are real advantages to a robust boil, and there is a price to.
If you are using Pilsner malt, one of the important considerations is the conversion of SSM into DMS and its ejection from the wort. The rate this happens is a half life reaction based on time and temperature, you need to be hot enough for long enough to get the DMS below sensory limits.
You haven't been boiling at 102oC for years (sorry) a 1.050 wort boils at about 100.6oC, there is a rule that says you cant heat a liquid above its BP (under atmospheric pressure), what you can do is change the rate the liquid boils at by putting in more or less heat.
If you are getting 8-10% evaporation, mission accomplished, provided the steam isn't condensing and dripping back into the kettle, which is always a concern when you leave the lid on or even partly cover the kettle. I wouldn't have a problem if you could arrange for any condensate that forms drips outside the kettle (seen some cleverly bent coat hangers used to do this)
Commercial kettles have condensate traps in the stacks (chimney) to stop condensate return.
If you are chilling in the kettle, yep the faster the better. As wort cools the amount of O2 that will dissolve in it increases.
No-Chilling hot avoids this, as does an inline wort chiller, its an open kettle with a coil stuck in it (or similar) where O2 pickup during wort chilling is an issue.
Thread has wandered a fair way off topic, might as well stay OT for a bit longer then bail.
I still don't believe 2.5kW will give a good boil in a 50L, my first reply to this thread was based on concerns about electrical safety, when you are pulling 15A bad things can happen very fast. Like this
When wiring 15A circuits, it pays to use very good quality parts, have as few junctions as possible, keep the leads as short as you reasonably can...
Posted it before but for Engibeer
Mark