Is the following rationale for sharing the gospel consistent with reformed theology? One can ask:


if one believes in predestination, then why share the Gospel?


A common response one often hears is:


because God also said to share the gospel or
perhaps God predestined you to be the one to share the gospel to cause this other person to become converted


I never quite found either response intellectually satisfactory. I recently came across the following, and wanted to see if it's consistent with reformed theology:


if you share the Gospel, and the person is among the elect, then you glorify God because you've brought someone closer to salvation (i.e. probably one part of a multi step program)
if you share the Gospel, and the person is not among the elect, then you also glorify God, for you have increased that person's sufferings in Hell, and it glorifies God to punish those in hell


Thus, one should avoid hyper-calvinism in only preaching to only those that one believes to be among the elect, but rather preach to all: for in either way, God is glorified.

Edit

Both of the responses below are beautiful. The flaw in my question is that "intellectual satisfication" is not a vaild measuring stick for biblical doctrine.
Perhaps the two "common" responses are not "intellectually satisfying", but at the very least, they are both highly biblical:


  And He said to them, "Go into all the world and preach the gospel to all creation." {Mark 16:15}


and 


  for "Whoever will call on the name of the Lord will be saved."
  How then will they call on Him in whom they have not believed? How will they believe in Him whom they have not heard? And how will they hear without a preacher? How will they preach unless they are sent? Just as it is written, "How beautiful are the feet of those who bring good news of good things!"
  However, they did not all heed the good news; for Isaiah says, "Lord, who has believed our report?" {Romans 10:13-16}


Therefore, it glorifies God to preach to all because His Word is being proclaimed, and we also know that His Word never returns "empty" {Isaiah 55:11 and 1 Corinthians 15:58}:


  So will My word be which goes forth from My mouth; It will not return to Me empty, Without accomplishing what I desire, And without succeeding in the matter for which I sent it.


and


  Therefore, my beloved brethren, be steadfast, immovable, always abounding in the work of the Lord, knowing that your toil is not in vain in the Lord.


While God's Will is ultimately accomplished - whether via displaying His grace or in pouring out His wrath on evil, He does not please Him to punish anyone:


  "For I have no pleasure in the death of anyone who dies," declares the Lord GOD. "Therefore, repent and live." {Ezekiel 18:32}


and


  "Say to them, 'As I live!' declares the Lord GOD, 'I take no pleasure in the death of the wicked, but rather that the wicked turn from his way and live. Turn back, turn back from your evil ways! Why then will you die, O house of Israel?'"  {Ezekiel 33:11}


The first point you raise, therefore, would be both biblical and in keeping with reformed theology, but the second point (regarding helping to increase punishment to Hell) is both unbiblical, and out of line with reformed thinking.