Do you have a square grinder? I tune most all my chains with my square grinder. In fact, after I spin up a loop off the spool. I immediately put it on the grinder, because I've set the stone dressers on the grinder to change the angles of the top plate and side plate on the cutters at a steeper degree than factory. It may not stay as sharp as long as the factory angles, but they definitely stay sharp plenty long enough, and my square tuned chains cut way faster than a factory square chain. A very considerable amount faster too. Not to be too cocky, but in my opinion. They actually make a factory chain seem dull compared to how my chains perform after the angle changes on the cutter plates.
I use a beveled file to touch them up every now and then in the woods if they need it. Usually from cutting to deep past the wood and into that brown soft stuff on the other side!
Wuts it called again?
Oh yeah, dirt!
Yes beveled files are more expensive than round files, but they last much longer in my opinion. Especially if just touching up a ground chain, and they can also be used to bring your rakers down when needed. Round files are great for removing gulets out of a square chain when nessasary. However I also use a grinder for that as well. I have the time, a large supply of saw chain and the equipment to grind. I feel grinding is the only way to go if you really want a perfectly tuned high performance saw chain with every cutter being uniform and perfect. Besides that, the chain simply cuts, faster, smoother, straighter, and is less stressful to bars and power heads. That's also why I throw ribbons and not chips in softer wood!
As far as steepening top and side plate cutter angels for hard wood?
I couldn't tell you if would be better than the factory angles or not because I have very little experience in hard woods.
Cut safe, stay sharp, and be aware!