If I were you, I'd be looking at something with more power. If your goal is to stay small, new and under the DPF requirements I'd be looking at a B2650.
I've had two different tractors with 5' RFM's. Still have a Ford 1210 HST 16 engine HP / 13.5 PTO HP with a Caroni mower since '91 or so. Had a Kubota B7500 HST with 21 engine HP / 16 PTO HP with a LandPride mower from 2002 till 2012.
All RFM's are not created equal. The Caroni is much lighter than the LandPride, and the Ford's 13.5 PTO HP handles it with ease. The LandPride was heavier and required all 16 PTO horses the Kubota could pump out, and it still was a bit too much going uphill when the grass was a bit tall.
I mentioned before that when I had those two combos at the same time, I swapped decks to see how it would go. The Kubota handled the lighter Caroni deck like it wasn't there, but the LandPride deck handled the Ford. Even with the two suitcase weights, the front of the Ford came off the ground easily and the 13.5 horses at the PTO didn't work out well at all.