My husband is a MQI shooter for 8 years and has been hard to get him to shoot much else ... but he did win a free PSE bow of his choice and he was wanting the Primos... he liked the combination of the ATA length,4lb bow weight, Speed and the 8 inch brace height.... although they didnt have that in stock he had to settle for a different model, which he was very dissapointed because he had his heart set on the Primos.
Make sure you read the PSE Bow Warrenty.
As for myself I am a fan of the Parker Compound Bows, I currently own 3 Parker Bows... 2 Ultra Lite 31's and the Parker Phoenix 34. I am very happy with the Phoenix 34.I shoot the Phoenix at a 26 inch draw at 50-60 lbs but mainly shoot it set at 57lbs.
Are you looking at the Phoenix 36 for your father?
The Phoenix 36 has a lower brace height of 6.75 compared to the Primo's 8 inch brace height, the Phoenix is matched in weight at 4lbs, same speed of 305 IBO, ATA is just a bit smaller.
I have never drawn or shot the Primo's so my comparisons are simply on paper
I find the Parker Phoenix 34 to be extremely quiet at the shot with all the Simm's additions to the bow... in fact I do believe it is the quietest bow I have shot, the setup with the new inline riser design really does aid in a quicker setup... they also come with the new Synprene grip which many a shooter praise but I myself am not a fan of the grip... based on I shoot an extremely low wrist grip.
The Phoenix is a very smooth drawing bow with a nice wall at full draw.... it dosent want to jump forward at full draw out of the hand when I relax, which makes it a dream to hold at full draw for extended periods of time.
Plus ya gotta love the camo idler wheel and cam....
I did switch the string out for a Stone Mountain Dakota Prestreched String and Harness... it seems a bit quieter and picked up a small amount of speed.
Check out the Parker Compound Bow warrenty... Parker has Top Notch Customer Service.
I think that if you all do decide on the Phoenix your father will be very happy with the bow, but what ever Brand Bow you all decide on your Father is a Lucky man to have kids like you going such a nice thing for him
I have taken a Turkey and 160lb Whitetail Doe with my Parker Phoenix 34 so far this year so I am very impressed with the bows performance
My Setup,

Parker Phoenix 34
Toxonics Sight
GKF Infiniti Dropaway Rest
Carbon Impact 3 Carbon Rod, 1 Tuner Stabilizer, 10 inch or so( I have found this stabilizer to work better on the Phoenix than any other stabilizer I have tried before including my Doinker System, The Carbon Impact Stabilizer is my ASA Competition Stabilizer but its working great for Bowhunting )
Stone Mountain Dakota Prestreched String
Custom Self Made Grip
Simms Riser Strip
Simms Limbsavers
Simms String Leeches
Speed Buttons
Simms LS Vibration Reduction Modules
Simms Mini Limbsavers mounted on Sight
Goldtip 3555's
Muzzy 4 Blade 100 grain Broadheads
Easton Nocks
Arizona 4 inch Vanes
Winn Free Flight Glove Release and or T.R.U Ball Chappy Boss.