I am also a recent convert to the forum's ticket website, with two purchases in particular highlighting the benefits of the system versus the TOC websites.
The first is a same-day return trip I booked from Hitchin to Barry Island for 19th July. While the tickets I've booked were offered by both GWR and the forum's ticket website (so no savings), the forum offered a seat selector for the GWR legs between Paddington and Cardiff Central, which GWR themselves do not offer. Being able to select specific seats rather than relying on the 'preferences' system giving me a good seat is quite the blessing.
The second is a trip from Stevenage to Scarborough for two, of which one person has a senior railcard, with the outbound on 5th August and the return on 9th August. Looking at departing around 11am from Stevenage on 5th August and returning from Scarborough around 11am as well on 9th August, LNER offered through advances for the trip that totalled just over £111. The forum's website, in comparison, was able to offer alternatives that cost only £80.60. The tickets were still through advances, so no splits were involved; the forum's website simply offered alternative itineraries to LNER. The itinerary LNER offered was:
Outbound: 1127 Stevenage to York, 1404 York to Scarborough
Return: 1048 Scarborough to York, 1202 York to Stevenage
In comparison, the forum's website offered:
Outbound: 1045 Stevenage to Peterborough, 1159 Peterborough to York, 1404 York to Scarborough
Return: 1048 Scarborough to York, 1220 York to Leeds, 1315 Leeds to Stevenage
I'm quite surprised that I could get a through advance routed via Leeds. While both journeys will take longer than what LNER offered, saving over £30 makes it definitely worth it. Add in that, like with GWR, I could use a seat selector for TPE's services.
As such, I will definitely be making more regular use of the forum's ticket website for sure