Slow cooking in a gas grill

Question

I have been looking at a Nepoleon gas grill for doing some low temperature (200 - 250 degree) slow grilling of some pork shoulders and beef briskets.  I have tried this on my Weber charcoal grill with great difficulty.  I can't hold the low temperature because the charcoal won't stay lit. The gas grill should solve the temperature problem.  And the makers of Nepoleon promote their product for this use, since they even sell a container to hold the smoking wood which is positioned over one of the burners to keep the smoke coming. Has anyone out there had experience with this Nepoleon grill (or other gas grill) used ffor this purpose?