HI PURPLERED I'M LITERALLY WEEPING WITH JOY OVER THE THOUGHT THAT YOU'VE RETURNED TO CRAWL AND MIGHT BE PLAYING AGAIN.
With that out of the way, let me address what you say here:
PurpleRed wrote:Remove teleport control and -cTele
-This REMOVES MOST OF THE FLAVOUR between pan and hell. For most builds I find I use distinctly different stratergies for pan and hell, this change would roll them into one.
-Removing -cTele and leaving in cBlink will significantly decrease difficulty of hell/zot5/tomb and leave us with cblink+apport as the one trick to rule them all.
-Overall I rate this a DECREASE in total game difficulty.
For your first point, this is a difference between the Hell ends and the pan rune levels which would be lost, but I don't think this loss is problematic. A recent trunk change made the named Pan lords have a chance of appearing on each new pan level the player enters if the player has the respective rune. So while Hell and Pan might share a more similar strategy of "get to rune, kill or avoid the boss" with -cTele gone from hell, there's still some differentiation in how that plays out.
For your second point, I think if cTele and -cTele are removed, I think there would be a change to possibly both the scroll and the spell where they gave only semi-controlled blink (like how currently the spell behaves under -cTele and how the blink spell behaves with +cTele status). I think we'd change the spell at a minimum, so you'd not be able to get a fully controlled blink all the way to the rune, just enduring or cancelling the contam. Blink scrolls are very limited and might not need any change,but changing those is also a possibility.
PurpleRed wrote:Remove ring of teleportation and *Tele property
-My personal experience is that injudicious use of Tele ring is one of the few ways I lose strong builds in extended game.
I do support making crawl harder, but not by shutting out tele like this. Tele could be tweaked, longer delay for example.
The complaint about ring of tele and *tele on equipment is more about how finding the ring means you never have to worry about losing a resource that is technically finite in a 3-rune game. You're not likely to run out of sources of teleport past a certain poin in the game if you only use the wand and scrolls, but if you do find the ring you have an incentive to use it to conserve the other two slightly better forms of teleport, yet the interface for the ring is a lot worse (put on the ring, spam the ability until it works).
Losing characters to overuse of the teleport ring like you mention isn't really what the ring is about. The scrolls and wand+recharge make teleport from other sources plentiful and equally potentially fatal. I think the ring is more about having the ring identification game and access to remove curse being more interesting, but there are probably better ways we can achieve that.
I'm not sure if really support removal of the ring myself because if you do run out of any form of teleport in a game, you have an incentive to grind for more of it to complete vaults where use of teleport is ideal. It's presence doesn't seem ideal but also not particularly harmful to me.