I have searched quite a bit on the internets but haven't found a good comparison of options for when the PTO fails as far as reliability, cost, and performance. My mini is fine for now but I like to have a plan if the dreaded marbles in a coffee can sound rears its ugly head from the engine bay. I know you can replace the supercharger with the same one but you're stuck with the same PTO problem. I've seen some who did an electric water pump which I find attractive because you bypass the PTO issue and it should free up engine drag because the motor no longer has to drive the water pump. I don't know the cost, performance, and reliability of this option. Also I hear a few aftermarket superchargers have an electric water pump?
Can anyone break down these options for me? Appreciated!

 

Been discussed many times...
But the simple fact is the SC is a WEAR item...
It is a big airpump, and eventually looses efficiency...
Some folks yank off the SC, and check the lube level, and refil as needed,...
This is about a 5 your job for a pro, and needs about $100-150 in gaskets, lube, etc...
My feeling is, it is nothing more than a $$ stopgap, since if the seals on the SC are leaking, you are going to go low again, and likely very fast...
A rebuilt SC with exchange is under $1000 for a top quality unit, and close to $600 for a cheap one...the labor to change one is MORE THAN THE SC...so pay for the labour ONCE, and you should be good for 10+ years.....lube it...might get a few more...overall costs higher unless you diy it.
Folks have talked if electric pumps, etc...none really work well on a daily driver.....and just load up the alternator, and adds one more failure point, with folks having multiple failures of electric pumps...
No electric pump will ever be as efficient as a directly connected mechanical pump...
Sure you might get a higher "peak" up on a dyno by a HALF a HP...but remember, a MINI is NOT A SPRINTER...IT IS A CURVY ROAD CRUISER...
On a side note...
I had a spare SC on the shelf for about 5 years...never used it...had my 2005 S for 10 years...fear of the SC failure Overblown? Maybe.
Mini basivly said the design life of the SC is about 10 years...then r/r the unit due to the labour involved when it fails...IMO this seems right.

 

So I can't do a replacement myself because of work constraints so it would be a shop doing it. Therefore topping up oil wouldn't be a great option.
Sounds like you're saying replace the supercharger when it goes, electric pumps aren't really viable for a DD?