While I get what you're saying, that simply wasn't the case in either combat. My character is a Mage; in both instances, he was safely in the back row while the frontline defenders locked down the enemy.
In both instances, I was trying to move my summon into position to 1) provide flanking to the party Fighter and 2) set it up so I could use its attacks next turn (having previously used a bigger, better attack on my first turn).
In the first fight, my Mage was on the roof of a nearby building, well out of reach. In the second fight, the enemy was immobilized by the Fighter while my Mage stood more than 5 squares away.
In both instances, my PC was in virtually no danger of being attacked. So sending my summon in didn't 'save' me two surges; in fact, it cost me a surge I would've kept, because when the summon blew up, I lost a surge.
I guess the lesson is not to bring out my summon until I'm ready to actually use it attacks. This would at least let me get off one attack before my minion goes boom.
But the main selling point of Summon Shadow Servant is that it lasts all day, instead of a single Encounter. That's not much of a selling point, though, when it's consistently dying the round immediately after it was summoned.
So while the idea of "saving surges" with summons is good in theory, it's pretty cold comfort in these particular anecdotes, and doesn't really apply in the case of bursts and blasts.