Kodak chemicals also work perfectly at room temperature, at least for Kodak paper. Tetenal 5 liter kit is probably the same in this regard. Only the 2.5 liter size was adjusted for lower temperatures.
But wait, what, Tetenal has discontinued the 2.5 liter kit?? If it's true, I can only say; I've been waiting for this day! It's quite rare that any discontinuation might do good for film photography, but this time it's true; this will mean end for endless hours of pain and bad results in darkroom with defective product, while market is still full of good alternatives that work! Buy the 5 liter version. It has separate parts for blix that are mixed by user, so it probably works unlike the 2.5 liter one. At least I'd guess, I haven't tried it.
Or, buy Kodak chemicals. You get 4 x 5 liter kits at almost the same price as Tetenal 5 liters:
http://www.ag-photographic.co.uk/kodak-ra4-developer-kit-4x5l-295-p.asp
http://www.ag-photographic.co.uk/kodak-ra4-blix-kit-4x5l-296-p.asp
This has been tried by many people at room temperature (as low as 20 deg.C) and it works. There are reports that Fuji paper might not work at lowest temperatures, but it's not been verified. This may well be true also for Tetenal 2.5 liter kit!
Cannot say anything about the Rollei kit, but hope this still helps. Kodak is cheap enough and lasts very long because it's packaged as four separate sealed 5 liter "kits".