Higher roll wins is pretty easy (with modifiers as appropriate), but it doesn't really handle degrees of success. You roll 112 hiding and the guard rolls 189 to spot you, was that an absolute success (where he gets a clear view of you) or a marginal one (where he knows someone is there but not who) or partial (where he thinks there might be someone there)? By the numbers, 189 is absolute but that doesn't take into account your margin of success hiding. Or what if you both roll failures, but you did worse at hiding than the guard did at spotting you?
RMU takes your margin of success (12) and applies it as a penalty on the perception roll. So 189 becomes 177 (absolute success), but if your hiding roll had been 134 the perception roll would have been 189-34 = 155 (regular success). If you succeed extremely well, your foe may even get confused (e.g. an amazing hiding roll could result in an absolute failure on the attempt to spot you, perhaps indicating the guard falls for your ploy and goes to investigate the wrong area).
But if you just want to know who won, and aren't concerned about the margin of success/failure, higher wins is perfectly fine and will give the same outcome.