So far no issue at all except for needing to switch on the DPF manually. It starts in manual mode to make sure you aren't surprised by a regen starting when you are in a building for instance. The tractor has a monitor mode by which you can select to see how your DPF is filling - it reads in percent. I switch to auto mode when I get to over 90% but it can take quite a few hours to get from 90 to 100% depending on load. My last job was moving bales, lots of accel and decel so the level rose relatively fast - like 3% an hour. Prior to that I got in 3 hours plowing and the percentage actually dropped because the exhaust temp at nearly 100% power is enough to burn the door out of the filter. If I understand right when the filter gets filled with ash, maybe between 5,000 and 10,000 hours, the regens will start getting so close together so it is time to take the filter off and have it cleaned. The dealer should have a list of paces that can clean a filter.
Prior to retiring a few years ago I worked testing new products prior to production. I retired just as we were building our first prototypes with Tier 4 interim. We used a system similar to Kubota's. I have lunch with my old team every few months and keep up with their test results. The actual field testing has shown our product will never need a DPF cleaning in the 10,000 hour design life but the product line is one that runs at low idle or high idle - there is no in between. Consequently the normal exhaust temperature when working tends to be hotter than say a tractor where a person wants to run at part throttle. My L5740, for instance, gives a burst of smoke with every direction change when using the loader. I assume that will be trapped because my M135GX runs a clean exhaust when used under the same condition.
During my regens so far the only way I have known it is getting hot is to switch my monitoring system around so one line will read exhaust temperature. If it wasn't for the light saying it was regenerating and the exhaust temperature climbing I would not know it was regenerating but all my regens to date have been while working pretty hard and steady - chopping haylage or plowing. I have a neighbor with a M100GX who said he had a regen light start flashing near the end of the day. He was in manual mode and waited until he was working the next day to switch to auto and let it regen.
Hope this helps.