Keep in mind the HST robs some power from the PTO (~19.5). My JD 770 which is 24 hp at the flywheel, had 21 at the PTO and never felt under powered cutting thick field grass with a 5 ft Bush-hog. My
L2501 with the same exact mower, bogs sometimes and I really have to back off if there is any moisture. I haven't run a tiller on either machine yet, so no idea how that would fair.
90% of the time I don't need any more power. For ground engaging, and loader work, its actually over powered for its weight.
I bought the
L2501 in 2017 for the same reason you are considering: no emissions. And just as you would expect, I haven't had any emissions related issues! Nor do I ever expect any. Purely speculation and opinion, but I feel that the
L2501 is quite possibly the most reliable tractor on market, with no bells and whistles and limited emissions equipment, it was the perfect replacement for my old 770.
But even with all of my boasting above, if I were to do it over, I'd be more apt to spring for the
L3901. Those times when I need more power are rare, but I need it to finish a side job. And while I'm paid by the hour, it would be nice just to rip right through those jobs without slowing down. From what I read here, its rare that anyone has any problem with the emissions system on their Kubota.
So long story short, don't be afraid of the emission systems. If you need the power for cutting and tilling, get it.