I understand your satisfaction with the hammer technique based upon your 100% success rate. I work in a bicycle shop, so my perspective changes a bit when I am working on someone else's bike. Using hairspray to aid in the removal makes a lot more sense to me than just banging away and I have a 100% success rate as well. I have found in bike cleaning, a chemical solution or chemical/mechanical solution is often a better way forward with less risk of damage and better looking results.
Non-Schwinn muscle bikes and middleweight bikes had some fairly thin walled grips (Hunt Wilde, etc.) that might not survive the hammer technique. But because they are thin walled they are easier to remove with hairspay, being fairly easy to pry up. If the grips are junky, then just cut them off regardless.
Either technique is obviously effective and yours is certainly quicker, although I don't recall ever having to deal with a hairspray mess as it evaporates pretty quick.
I am not trying to convince you otherwise, or carry on a debate, but my info may be helpful for other folks to consider in finding their way forward and what may work best for them in various repairs.