Yes, I have just ordered a pair of T31EVO GTs to replace my existing T30 Evo GTs.
Before reading the next bit, you need to know that I normally get a tad over 5,000 miles from BT020 F rated tyres, front and back. We ride two up, often fully loaded and we live in the Yorkshire Dales - roughly surfaced roads, narrow country lanes, lots of accelerating and decelerating - not particularly aggressively. But compared to many others on this forum, I get through tyres quite quickly. 5,000 miles has been a constant on both of my ST1300s whenever I have had BT020s fitted - which is most of the time.
So - my current T30 GT Evos have about 1mm left to the wear bar, and I reckon that this will go down to the wear bars in the next 100 miles, if that. The last bit of tread disappears surprisingly quickly. So that will 4,500 miles, which actually compares well to the BT020 given the benefits.
The fronts are pretty good, and the last time I had the T30s on, they lasted much longer - 6,100 before I changed them - but I had to change early as I needed fresh tread for a long tour.
I like them, apart from my low mileage, but they provide a good, confidence inspiring feel and the pattern of wear is nice. The BT020s tend to wear down in the centre first, with plenty of tread left on the outside. This resulted in a marked squaring off 'edge' which was noticeable when starting to lean in to a bend. Nothing dramatic, it was just a feel that was there.
The rear BT023s tended to wear on the sides first - these would be scuffed up badly and started to feel odd in the corners and would begin to wallow through the bends, a bit like riding on an underinflated tyre. The fronts lasted longer and were fine.
The rear T30GT Evos have worn down in the centre first, with a minimum of squaring off - although the tyre has worn a slightly different profile, it is still a smooth rounded transition between the centre and the sides, which is nice.
I normally change both tyres at the same time, but at this stage I wouldn't normally bother changing my front tyre. However, We're off for a 3 week trip to Scotland before long, and I suspect that they won't last 2 - 3000 miles. I may be wrong, but I'm not going to risk it. I did that once before, ran out of tread and it cost me more to get the bike back home than it would have for a new set of tyres. Never again !
Oh - one other bit of info When new - Rear T30GT Evos have 6mm of tread to the wear bar in the centre and 4.3mm to wear bar half way between the centre and the edge.
At 2,200 miles (about half life) I measured one set at 3mm centre and 2mm sides.