The push button control for PTO engagement isn't necessarily a bad thing as long as the control has some electrohydraulic smarts behind it.
In the Deere line, all their AG tractors from the 6020 series and up have push button PTO switches. However, they specifically mention that the PTO control has "electrohydraulic controlled modulation to ensure smooth engagement".
In the 5025 series, the push button "eletrohydraulic" PTO control is only included with the new 24F/24R transmission (also electrohydraulic). They still use a lever for PTO control with the ability to "manually feather the PTO for smoother engagement" with the 9/3 and 12/12 transmissions.
I also spent some time with Deere's online 4x20 CUT operators manual to see what they say about PTO engagement. Sure enough, it boils down to stopping the tractor forward motion (reverser in neutral, foot off fwd/rev pedals on eHydro), reducing the engine RPM to 1500, pull the PTO knob, and speed the engine RPMs back up to 2400 for rated 540 RPM PTO speed.
Well, I must say that IMO this is a definite area for improvement on the 4x20 series CUTs. Especially since I'm finding out through TBN that other CUT brands do have live independent PTOs with modulated (manual or otherwise) engagement.