I had a QS1 and a Venture One (both under 5k). I combined the V1 into my QS1 so I ended up with a 7.25k QS1. Once I PC'd it to a QS, I ended up getting a WMC.
A product change when you're already surpassed $5k seems to grant you a WMC without you having to fight with chat/calling for one. That's if you care about a WMC of course. People just like the look of it on their card (myself included) 
@UncleB wrote:
@Anonymous wrote:
@Anonymous wrote:Like the title says, I have an upgrade available. Who has done the math on 1.5% vs. 1.25 miles? I fly often and have a couple 100K miles with 2 airlines normally sitting in my rewards accounts. Just looking to see what is the best deal.
It's not often that I am the contrarian voice, but you may want to consider the V1, at least for a while - reason being that if your CL qualifies (none of this matters if your CL is less than $5000) it will be a WMC, whereas the QS will likely remain a standard card (opinon based based on my recent PC to QS with a $7k CL - I was hoping for WMC and did not get) - you can then PC again to QS ins 6 months, and keep the WMC
Actually to get a WMC is the one of the only reasons I can think of to go with the V1 (temporarily).
That being said, I always thought that if the WMC option/upgrade was available for the Venture One it would be available for a PC to Quicksilver as well (assuming the credit line is over $5k), but I guess that might not always be the case.
I'm fairly sure I've read of people going from QS1 to QS with a credit line over $5k and it coming as a WMC, but perhaps it's YMMV.
That's the only reason I PCed a QS to V1. I quit using it and then PCed back to QS, and it's now a WMC.
If you outright apply, the V1 has a better sign-up bonus and longer 0% promo period than QS, so it's worth getting in that situation. If you're PCing, the QS makes more sense due to the higher rewards rate (1.5% vs 1.25% with limited redemtion).