But in my time of commuting in the MML, there seem to have been just as many major issues on the ECML. E.g. At least 3 major evacuations of Kings Cross box, various wires down incidents (many more than on MML) and the almost routine problems in the Moorgate branch.
This simply isn't my experience. I use GN on a regular basis, on a comparable level to a commuter although I don't necessarily travel at traditional times. Sure issues do occur, but for example I can't recall a single day this year when I've found the service to be badly disrupted to meltdown levels -- with the notable exception of the current driver availability shambles. In fact, the last day I can recall when I have used a service comparable to the regular Thameslink meltdowns was the 27th December engineering work overrun shambles of a couple of years back. The general GN experience is you turn up at the station, the train turns broadly up on time, and by and large you reach your destination broadly on time -- especially in the down direction.
Sure, things happen, sure delays happen from time to time, but in general the service is reliable and dependable. On the comparatively rare occasions when things do go wrong, however, late running can quickly snowball due to the combinations of stopping patterns clashing on a congested railway.
If something goes wrong on the Peterborough line, you still have trains reaching London from the Cambridge line. If something goes wrong between Stevenage and Alexandra Palance then you have the Hertford loop. Large proportions of the route have four (or more) tracks. We don't have to worry about getting caught up with third-rail problems like during ice/snow.
These factors, combined with the simple statistical probability of less mileage meaning less chance for things to go wrong, *guarantees* Great Northern will always be more reliable without Thameslink. The regular Thameslink meltdowns which seem to be happening on a regular basis just keep on demonstrating this, and it's about time DFT and others woke up to this reality.
The one major difference I notice is snow, where the MML service packs up but the ECML keeps working. I put this down partly due to the 319s which really don't like the snow, whereas the 365s and 313s cope much better. It will be interesting to see how the 700s get on.
Glad you acknowledge that the GN is normally pretty good in winter weather. The 317s/321s seem ok in winter weather, wonder why the 319s should be such an issue?