I've been using CQG since 1992, but eSignal and a host of other charting packages will do a perfectly adequate job with stock pairs and futures spreads of all persuasions.
For charting, eSignal is at least $400 cheaper per month than CQG, and both are perfectly adequate. I have used CQG for spreads since 1992, but just added an eSignal subscription as well. The CQG base price less exchange fees is $595/month compared to $195/ month for the eSignal. For charting most of these platforms are on a monthly subscription, so as the trader builds equity he can upgrade quickly. In terms of execution, the clients who want to efficiently trade spreads at a higher intraday frequency generally spend more on execution platforms than the day or swing spread traders. $18K per month for Apama or the free IB stuff. 75% use the TT. It is crazy that I have clients spending $500 per month to trade and I have some that spend $20K per month. And no, the earnings are not linear and in some cases surprising.