Tested it directly on my 600D and thanks for the hint about Magic Lantern. Be prepared for the wall of text you see below these 2 introducing sentences

My test results, first thing that strikes me is the removed delay shutter option. AFAIK for canon this is a separate button on their remotes. The real problem is that there's no delay option anymore. As the intervalometer starts counting AFTER the first shot, maybe you should make a extra timer which delays the first shot with x seconds. Where x can be a same input field as now you have with the interval timer.

Also I managed to make pierogi crazy, regarding the intervalometer. I set up 5 exposures, interval time 5 seconds and pressed start and locked the screen. Somehow pierogi came in a loop and it kept sending shutter release commands at about 0(continues burst like) seconds interval for about let's say 20 exposures then I moved my N900 away from the IR sensor and unlocked the N900 and it continued to sending commands and after about 2 seconds after the unlock it starts counting normally again.

While I am writing this post, let say if I can reproduce:

Set let's say 8 shots, at about 5 seconds interval.
Press start, lock the screen, sometimes the camera starts to continues shoot. As it picks up like the shutter button is hanging on pierogis side) And it recovers with a delay of about 2 seconds after unlocking the N900 again. These "burst" shots while my N900 is locked are not counted in pierogi as actual shots. I think it recovers after the next exposure is meant to be.
So what I think is that as soon you lock, pierogi starts to issue commands to release shutter at almost continues rate, and recovers only at the next interval ( both locked and unlocked - edit: confirmed). These continues shots are not counted in pierogi as actual exposures as seen in the shots left counter after unlocking again.

It happens not always, but at a rate of about 8 out of 10 times.

Regarding the VIP1853, I will test that later but I can't think of environmental issues as the original remote works fine and besides it's sensor is 5cm away from where my TV has it's sensor and that remote is working fine with pierogi from the couch... Hard to imagine these 5 cm would hurt that much, as the original remote has no issues and my other pierogi controlled stuff also hasn't any issues so if it were me to say: It has to be something in the protocol that's still not right... Will report back later what version 1.1.29 has to offer my VIP1853

edit: As for the VIP1853, all commands work however the receiver is still very very picky. But range doesn't matter, I even managed to turn it on from the couch thus 6m. But still required more taps to get in recognized, however better than in previous versions, I think. It was already that sensitive I managed to test all buttons and can confirm they work. But for general use it is not sensitive. I have the feeling I have to point the n900 in almost a straight beam to the irsensor of the box to make work... I beginning to think this box has a very picky sensor. Going to channel 302 is not achievable as you never seem to know when your commands get send or better said, received. Sometimes you end up on channel 32, the other time you stay where you were the other time it gets you to channel 0... Will try to play with the debug settings of duty cycle and frequency.

Edit2: See pictures attached. The light spot on my TV is the IRsensor and the circle on the Motorola-device is I believe the IR sensor. My TV works beautiful with pierogi so you would say the motorola would also do so, but it doesn't...

Also I lost a favorite keyset, the samsung DVB-T receiver keyset. I guess you named it Samsung Set-top Box keyset 1. Can you confirm as that's what some of my friends use but I just want to be sure I have the right keyset available in my favourites when the occasion comes I need it.