Hey,
I recently moved over to Reaper after years of working on other software, including Cubase, Nuendo, Logic etc...
Firstly, I have to agree with Tedwood when he says that the only way to evaluate it is by trying it out. It is a very non-invasive installation (a few Mb and no system files) and so can easily be deleted without any pain. Reaper does offer a very different take on Audio production and its full capacities have to be explored to be appreciated.
In terms of your questions, I can only answer a couple of them.
1/ Sampler. Yes Reaper does come with its own sample player. You can read about it here:
http://www.cockos.com/wiki/index.php...mplomatic_5000. As for drag 'n' drop...it has an "import a selected sample from arrange" function rather than drag and drop.
2/ Upsampling and conversion: My impression of Reaper is that it reads the file format directly without conversion. I might be wrong but it reads directly from a source file. So if you record in 24bit, it will read in 24bit. If you record in 192kbps mp3 (but why oh why would you want to?) it will read that format directly. The 64bit processing path applies to the way the audio is treated in the rest of the programme, through plugins etc. So no useless conversion there...
3/ Device panels...Can't help you there...
4/ Groove templates, I don't think so. At least I have not yet come across one but there may be an equivalent. However, considering the frequency of the updates from the developers there is nothing stopping you asking for one.
Reaper, thus far, has performed admirably. It does require a certain amount of adaptation in order to get around the routing and some of the more detailed options. But it is light, stable and powerful.
Lastly, and on a slightly more personal note (if I may) their licence is admirable.
I am sure that I will find things in time that I might wish for, but I will not hesitate to put them on the wishlist for future versions. However, the user forum is a strong one and there are a lot of users who are suggesting many constructive improvements. An excellent asset to the development team.
Anyway, try it and see. Costs nothing and you have a lot of time to figure it out!
Hope this helps...