That Canon cooker which you had was a fine piece of kit. I may have even sold it to you if you live in Leicestershire.
Canon Cookers are still available, with the self-clean linings. Look for the Indesit Graded Centre adverts in the Leicester Mercury, they supply them at very reasonable prices.Personally, I would not buy a cooker without them, they save so much work.
It is true that with a gas oven you can cook dishes requiring different temperatures, and they are particularly good for cake baking, because they give an nice brown finish on the top of a Victoria sandwich for instance.
But, very few people cook a complete meal in the oven nowadays, not many people cook puddings in the oven for instance, so there is not too much difference now.
The hob is a completely different story, the gas hob is much superior in my opinion.
The difference in operating cost is really not very important, because it is the heating appliances that account for the majority of the fuel account.
Gas cookers are still very long lasting, and often outlast all the other appliances in the kitchen.