It'll have a job as it's not a condensing boiler
In my tests I certainly found that it uses less gas. It's hard to monitor due to weather conditions, but I try to log them along with my readings. I've monitored for all day usage over a couple of years now (We've lived here 4 years and had HR92s from new) and it's pretty consistent in the readings. Whilst it doesn't use considerably less gas than timings, it does use less. My theory is that you're heating the fabric of the house. A very well insulated house should in theory have little heat loss, so keeping it at a set point all day should in theory use less energy than letting the room cool then reheat - as your then having to heat everything again, not just the room but the fixtures and fittings and any walls etc.
However I do have a very well insulated house (My front door has a U value of 0.87). In a house that's older, poorly insulated, and has lots of drafts then I can see how you'd use more gas. For example my parents have a HR92 in a rear porch where theres a draft from the cat flap. If they use a 16oc set back on this rad it just runs 24/7 - maybe an extreme example but in a house where your heat losses are great then I can see how timings prevent a system from overworking.