I did buy one of the TR-08s, but I sold it after a short while as I found the lack of proper pattern chaining too big a compromise. I was given a TB-03 in exchange for a mixing desk I wasn't using, and I ended up giving it away as it sounded 'OK' but it didn't wow me and in the end I never used it for that reason.
I've steered clear of the rest of the Roland boutique stuff as a result. A friend of mine has had a few of them but never kept any, and I tried them all out and I felt 'meh' about them. I can't put my finger on it and it's very subjective but to me they don't have any personalty or charm.
The TR-08S looks on paper to be a very interesting device but I'm surprisingly (or maybe not, in light of the above) un-tempted. Also, looking at their guts they are extremely dense chips - most of them seem to be the same board running different software, and I have some (relatively minor, but ...) concerns about their longevity.
That said, I've not really been a fan of Roland synthesizers and drum machines since the days of the D50 and earlier. No denying the mighty Jupiters and there was something about the D-series boards that I did like a lot, but I just don't like 'the Roland sound' since then for some reason. Again, that's purely subjective.
If the RD-909 is anything like as good as the Model D clone then I'll be in line. Even if the sounds are a bit cliche now, they can be processed and also, I'm hoping, layered with external drum sounds driven over MIDI.
I'm currently more interested in a Squarp Pyramid than anything else, strangely enough ... but I'm going to have to be patient and wait a month or two to justify the pennies if I decide to go for it