As Phal stated, it depends on three real factors. SSID configuration. Client capabilities and cleanliness of the RF environment.
The R610 is 3x3:3, meaning as you stated it can achieve a mac MCS rate of ~1300 Mbps.
You can configure an 80 MHz wide channel SSID but if your client device is only 2x2:2 or 1x1:1 or does not support 80 MHz wide channels, it will be your limiting factor. Basically the least common denominator would decide the max achievable data rate (MCS Index - http://mcsindex.com
Likewise if you configure an 80 MHz wide channel but 20/40 of it is highly saturated by other networks within range, you would most likely see a drastic reduction in throughput as wireless is very much a shared medium.
Even in pristine conditions and assuming your client is 3x3:3 capable as well, you'd only ever get maybe 70% of that 1300 Mbps rate at best. And more than likely it'd be somewhere between ~50
and 70% of the spectral efficiency.