The only problems I've had with 10% ethanol is that it rots out old rubber fuel lines in a hurry (I've had this on four cars). It doesn't seem to bother more modern rubber once you replace the old ones. I suspect the same is true of injector seals.

There's nothing in an SU carb to rot except a small O-ring where the line to the jet enters the bottom of the float bowl. I have not had trouble with that.

I've never run higher percentages than that in a Volvo, but octane rating is octane rating, period. I don't foresee any tuning problems as a result if the octane numbers are there.

With unleaded gas of any sort (regardless of ethanol content), you'll need to install hardened valve seats if/when you do a valve job. It should not be necessary to do that if the valve seats ran for a while on leaded fuel, which actually hardens the old-style seats over time -- but once you grind on them, they're goners.

The other thing is that gas is what lubricates the valve stems in their guides. Modern unleaded supposedly has lubricants that substitute for the lead that used to do that. Be sure the ethanol mix has something equivalent.