It's not just oil bearing clearances that you have to be concerned with, forged internals especially Pistons create what is called piston slap upon start up. Because they are forged they are heat treated and have little to no room for thermal expansion to take shape like it does in the cast aluminum Pistons.
Now Mahle has attempted to correct this issue by creating something that's called a Hyperutechtic Piston. It's stronger than your standard cast piston but not as strong as a forged piston. It does though help elevate piston slap in the cylinder bore by allowing some form of thermal expansion.
Now when it comes to things like bearing clearances, these are so precise that Subaru literally recommends getting new case halves and a new crankshaft IF engine work/replacement is to be done. The tolerances are so finite that when you change one thing it ends up becoming a domino effect. The bearing clearances change, you run thicker oil, because you run thicker oil, the volume the pump creates is inadequate because the pump was designed for a specific oil thickness to be used. That's generally the reason why if you have ever seen any of the powerblock TV shows like "engine power" you always hear them changing out the oil pump for a performance unit from either milodon or Moroso when working with those big V8 blocks.
Now sure any shop who can build you an engine is going to spat reputation and customer success they personally have at you. Why? Because they are just trying to sell you a product. They are trying to get you to spend your money with and on them.
To answer your question of reliability and power? No such thing. Hands down no such thing as reliability AND power.
If you have power your going to break shit it's just a question of when.
Now there are plenty of Subaru's out there on both ethanol and pump gas making modest numbers with a larger stock frame turbo WITHOUT forged internals. I honestly think the majority of engine builds happen just because of the ringland scare. I see a bunch of STi's and WRX's for sale that have a built short block yet everything else is stock. From the heads all the way to the turbo and TGV's. There is no real reason to put forged internals in the car unless your shooting for 500 + horsepower.
Now take it from someone who has owned a couple vehicles touching the 700 to 900 hp range.
It's fun at first, but the shit gets really old really fast. Drive ability goes in the toilet, forget trying to drive the car the way you did when you bought it or even when it had just some bolt ons. That's history. Sure you see YouTube videos of all this roll racing crap on highways. STi beats Evo, STi beats viper, STi beats street bike. BUT what they don't say is how often does the car run like that? How's it drive everyday in NORMAL traffic flow? I'll tell you what it's like. It's a PITA!!!!!! It stumbles, idle is usually hunting and pecking in stop and go traffic, the heat soak is pretty intense with a big build if your in stop and go traffic as well. And because your fast, you have to deal with not only the other cars but law enforcement CONSTANTLY. They keep tabs on the cars that are stupid fast on the road.
So classroom instruction aside. I say especially if your looking at E85, I would go with a 20G or DOM series Blouch turbo, headers, Uppipe, FMIC, TGVs, intake manifold porting, 1300cc injectors, 300lph pump, either cobb or GS EBCS, and as much heat isolation you can do and that should get you close to the 400 to 450 range with E85.
