We started with the Peg Perego Primo Viaggio SIP 30-30 infant seat and at 6 months, he's close to being too tall for it so we picked up the Primo Viaggio SIP 5-70 Convertible this past weekend.
We tried mounting the Recaro ProRide and it's a bit taller than the Peg thus reducing front passenger leg room. Right now, we can have someone around 5'10" to maybe 6" sit comfortably in the front passenger seat.
We were sold on the Primo Viaggio SIP 5-70 Convertible after test fitting it and really liked it's build quality.
You can see how much space the Peg leaves between the seat and the top of the door opening - the Recaro had significantly less room and we pretty much had to have our son in a near horizontal position to get him in and out of the seat:
Note that the M3 does not have any place (that I could find) to latch the back of the seat down and with the help of the dedicated sales rep at the baby store, we came up with this solution:
And this is how we cinched it down to the mounting bolt of the front passenger seat:
The rep gave us the extra piece to loop around the bolt so it's something that you'll have to find and purchase.
We also had to purchase this for $4.99 to help keep the seat parallel to the ground since the M's seat base does sink down toward the seat back quite a bit: http://us.diono.com/en/car-seat-accessories/sit-rite