Can the MacBook Pro 2015 13'/15' run two external SST 4k displays at 60hz?

I need to replace my old MacBook Pro and would buy one of these models:

• MBP 13' 2015
• MBP 15' 2015
• MBP 13' 2016
• MBP 15' 2016

I would prefer the 2015 model. In about one year, I would like to drive two external 4k displays of the new computer. I can choose which displays I will buy (SST for example). It is important to me, that both displays run at 60hz.

That leads me to the question:

Can the MacBook Pro 2015 13'/15' run two external SST 4k displays at 60hz?

Trying to find an answer, I did the following reading. Unfortunately I could not find a straight answer to my question.

Using 4K displays, 5K displays, and Ultra HD TVs with your Mac

https://support.apple.com/en-us/HT206587

With OS X Yosemite v10.10.3 and later, most single-stream 4K (3840x2160) displays are supported at 60Hz operation on the following Mac computers: … MacBook Pro (Retina, 13-inch, Early 2015) and later. MacBook Pro (Retina, 15-inch, Mid 2014) and later

Unfortunately it does not state whether two displays can be run at 3840 by 2160 at 60hz

MacBook Pro (Retina, 15-inch, Mid 2015) - Technical Specifications

https://support.apple.com/kb/SP719?locale=en_US

Simultaneously supports full native resolution on the built-in display and up to 3840 by 2160 pixels on up to two external displays, both at millions of colors.
…
Support for up to 5120-by-2880 resolution at 60Hz on a single external display (model with AMD Radeon R9 M370X only)

Unfortunately it does not state at what frequency the 3840 by 2160 displays can be run

MacBook Pro (Retina, 13-inch, Early 2015) - Technical Specifications

https://support.apple.com/kb/sp715?locale=en_US

Simultaneously supports full native resolution on the built-in display and up to 3840 by 2160 pixels on up to two external displays, both at millions of colors.

Unfortunately it does not state at which frequency the displays can be run

Dual 4k support for MacBook Pro Mid 2014

https://discussions.apple.com/thread/6516153?answerId=28722298022#28722298022

60 fps with MacBook Pro 13" 2015 & Samsung JU6445

https://discussions.apple.com/thread/7227180

Retina Display MacBook Pro Q&A

http://www.everymac.com/systems/apple/macbook_pro/specs/macbook-pro-core-i5-2.7- 13-early-2015-retina-display-specs.html

This model supports a simultaneous maximum resolution up to 3840x2160 on two external displays via Thunderbolt 2

Retina Display MacBook Pro Q&A - Updated June 25, 2015

http://www.everymac.com/systems/apple/macbook_pro/macbook-pro-retina-display-faq /macbook-pro-retina-display-how-to-manually-switch-graphics.html#extdisplays

Apple reports that the "Early 2015" MacBook Pro models (MacBookPro12,1) as well as the "Mid-2015" MacBook Pro models with integrated graphics (MacBookPro11,4) support a simultaneous maximum resolution up to 3840x2160 on two external displays via Thunderbolt 2.

But at what frequency?

Does anyone have first-hand experience?