Democrats Please Choose A Democrat Ballot - Republicans Please Choose A Republican Ballot

Today I received a mailer from the Illinois Common Sense PAC it reads:

This years democratic primary has almost no contested races.
In this primary , please Vote for Ron Sandack by choosing a Republican ballot.

The following post was written by Bruce Beckman a Democratic Precinct Committeeman from Downers Grove Township, Bruce explains exactly why Democrats should not pull a Republican ballot.
  
A Republican candidate in the 81st is begging everybody to crossover and select a Republican ballot. What they aren't telling you is that once you do that, you are seen as a Republican by the Board of Elections and cannot participate in the selection process of the Democratic Party. While it is your full right to do this, please understand the implication of this move.

There are those who'd like you to believe that selecting a Republican ballot is the righteous thing to do when in fact it only serves the wishes of the Republican candidate.  When you select the opposing party's ballot, it is not for one office, but all of them.  At the same time it weakens the party which best matches your views.  Rather than bidding the wishes of the Republican candidate, select the ballot of the Party that matches your vision for the future.

The general election is in November and that is when the 81st Rep is selected.