There was propaganda art that he even went to the front line, although he seldom did, that is if he really did. However, the troops believed it. So in terms of the military it may not make a difference.
Him being gone could be a good time for someone to plot and have Stalin overthrown, but given the situation at the time that may do more harm than good.
Actually, his only visit "to the front" was in 1943, and even then he really didn't go anywhere near it. Robert Service described the visit as follows in *Stalin: A Biography* (Cambridge, MA: Harvard UP 2005), pp. 456-7:
"When he got to within thirty or forty miles of active hostilities, he was greeted by military commanders on the Minsk Chaussée who advised him that they could not guarantee his safety if he travelled further. Stalin must have known that they would say this. This was the nearest he approached to any point of direct action in the war. He never saw a shot fired. But he made much of the conversation with his commanders and, after due display of disappointment, returned to the Kremlin. Much was made of the journey in official propaganda. *Pravda* reported it as if Stalin really had reached the front and given much needed orders on strategy and tactics to the frontal command.
"Mikoyan told a less flattering tale of the journey. 'Stalin himself,' he wrote, 'was not the bravest of men.' Allegedly Stalin, as he talked with commanders, felt an urgent call of nature. Mikoyan speculated that it might have been mortal fear rather than the normal effects of digestion. Stalin anyway needed to go somewhere fast. He asked about the bushes by the roadside, but the generals--whose troops had not long before liberated the zone from German occupation--could not guarantee that landmines had not been left behind. 'At that point,' Mikoyan recorded with memorable precision, 'the Supreme Commander in sight of everyone dropped his trousers and did his business on the asphalt. This completed his 'reconnoitring of the front' and he went straight back to Moscow." (In a footnote, Service gives his source as Mikoyan's *Tak bylo: Razmyshleniya o minuvshem*, Moscow, 1999.)