The randomness inherient in the game can pose an obstaclle. It sort of depends on just how story driven you want to run things. The randomness can also help to inspire a GM in new ways too.
It's hard to say if MRQ will suit your style of play without actually seeing you and your group actually gaming. Differernt gamers like differernt types of play. Some people love dungeon crawsl, and being sent from place to place by the story. Others don't like th be led round by the nose and prefer to have a impact in the direction that the campaiagn follows.
One thing to watch out for is that players usually want to be active participants who can have an effect on the outcome of the adventure,. If a GM is too dedicated to following a storyline, thing don't go well. Basically, if the players can make a difference, then they will get frustrated. THat is the big difference between RPGs and other forms of fiction.
One thing that might help, is that you, as the GM, are the one who works up the stats for the NPCs. You are also the one who presents the NPCS in the adventures. THis gives you a lot on control over just how much of a challenge any given encounter will turn out to be. This lets you fine tune things, allowing you to "force" events and outcomes much the way a stage magician does. You can stack the deck, use misdirection, and any othet trick you can think off to help guide things along a certain path without looking like you are forcing things.
As others have mentioned, giving out a few more hero poinbts can help to prevent or at least mitigate the occasional "unlucky hit" that might dirupt a storyline.
Just be careful with how much you do to enforce the storyline. In addtional to the desire to have some control over thier characters and the coruse of events, players also want to feel challenged. If the players think that they are not being challenged they will get bored. The key word is think.
No matter what you do, there will always be some uncertainty to the outcome of any encounter, thanks to the dice, and the free will of the players. Ambushes can be lethal, don't ambush your group too often if you want them to live, or at least make the ambushes bad shots. Tactics and planning go a long way, and players have a funny way of snatching defeat from the jaws of victory. I once wiped out a group pf experienced RQ characters with a bunch of wimpy Trollkin. The Trollkin were holed up in a house and the players just diided to try a frontal assault. Some of the group were taken out by missile fire on the way up to the door. The others were taken out when the group moved back after discovering that the door was barred from the inside. Others got picked off trading missile fire, not good since the PCs were standing out in the open while the Trollkin were shooting out if windows and had cover. The PCs were so embarassed at being driven back, that the remants did a second frontal attack where they finally fell under a hail of (sling) bullets. Made all the more shameful since no one bothered to recon the area, and so failed to notice that there were no windows on one side of the house, or that there was a hole in the back wall of the house. Naturally, that encounter was a disastrous setback for the storyline of my campaign.Yet, had I done anything to change the outcome, the effects would have been even more of a disaster.
So in the end it boils down to just how heavily plotted is the storyline for your adventures, and how much can the group divert from the plot without disrupting things, an then hoping that the group doesn't do something dumb and unexpectedly suicidal.
