Hi robrenz,
It could. But its hard to say what will happen.
MOV work by shunting the surge current to ground; if the ground is somehow removed [ that's why good surge protectors have a ground fault light] the MOV will absorb the energy.
A high joule rating [ akin to a high watt rating on a resistor] will then absorb more energy before it blows, and MOVs that blow are like a flare and very hot. At worst it can melt plastic cases and if it breaks through, can burn the surrounding area of the surge protector, like a carpet or a sofa. These high joule MOV are best in all metal cases. If the MOV absorb the energy and do not blow, then nothing likely will happen, and the good news is the partially damaged MOV will likely blow at lower energy at the next surge, whenever that is. The downside is that high joule rating MOV are a fire risk.
To avoid this, plastic cased surge protectors are best with small joule MOV, so they will die quickly and not have too much energy to dissipate. Many surge protectors from reputable power product companies like APC bypass the hype and usually just have 300-500 joule MOV inside them and will offer a lifetime guarantee on the product, because surges that damage protectors are fairly rare and the cost to replace the unit truly small.
To get higher joules some surge protectors makers either parallel multiple 100-500 joule MOV or use one of the newer premade single unit parallel MOVs.
MOV are non-linear and when faced with surge voltage, identically label MOV will not act identical, some will have let through voltages lower or higher than spec. This causes one of the units in parallel to blow sooner than others, so you don't have the violent burn expected of a single high joule MOV.
Alas, better designs include a thermal fuse in series with the MOV. If the MOV overheats, the fuse will blow, cutting off the MOV from the line thus preventing an explosion. If this design is used, all the joule ratings become moot, because the thermal fuse is often designed to trip before the MOV can explode, making high joule ratings unnecessary.
Better designs have MOV also linked by a thermal fuse to the HOT side of the AC line. If the MOV overheat, the HOT line thermal fuse will blow, killing all power to units serviced by the the surge protector, again preventing a MOV fire but also killing the whole protector.
Thus, in the end high joule ratings are a fire risk, and if thermal fuses are used, will unlikely provide the benefit of making the surge protector last longer against surges.
Based on work done by NIST, a joule rating of over 100 is adequate. Over 300 joules allows for a 3x derating is likely more you'll ever need.
Would the higher capacity in joules (more or larger MOV's) equate to yielding a longer life?
High joule rating for a surge protector is a misconception. Here's a thread on it from a year ago.
https://www.eevblog.com/forum/index.php?topic=381.msg19635#msg19635
http://en.wikipedia.org/wiki/Surge_protector#Joules_rating
Based on work done by NIST, a joule rating of over 100 is adequate. Over 300 joules allows for a 3x derating is likely more you'll ever need.
Would the higher capacity in joules (more or larger MOV's) equate to yielding a longer life?