As many users I do also have problems with SONY device and pierogi .

SONY Compact Disc Player CDP-XE370
(thank you for so fast keyset addition)

So range here is not a problem. It is working even from 3-4m .
The problem I do have is that many keys only work when I tap very fast a button (very very often I had to tap it very fast like 3-6 times to get reaction).
When I do push constatnly a button or tap it with normal typical speed the there are like 30-50% chance that there will be no reaction.
With vloume buttons 100% ( only very fast tapping works).

I'm not sure how good it worked in qtirreco (few updates ago it stoped working for me) since its interface was crap and you had to tap fast buttons to not move them by mistake but I think that it was a bit better.

I did check it from very close range and far range.

Power, mute buttons dont work.
Rewind buttons dont work when taped constantly only do rewind few sec forward, back when single taped
Missing fade button.

Tested on 1.1.2, all SONY CD keysets

update: I did test it a bit more and rewrote a bit my observation.
update2: I am using also my n900 as remote for Philips, Lg, Panasonic TVs, JVC DVD and it works nice so it shouldnt be my device problem