Tight tele boots are not fun, your feet will always be cold due to constricted circulation, toe pinch can be more of a problem, and a host of other foot problems can occur if you spend a lot of time in them. This does not mean that I think you should get your boots so big that your feet are swimming in them, just that given the choice I think it is easier to find ways to take up a bit of room than it is to create more room in plastic boots. Remember, take your time in the shop fitting your boots. Modern telemark boots last a long while so a little extra time spent here only makes sense. Listen to the shop person's advice if you think they know what they are doing but prepare yourself and trust your own judgment as well.
Many telemark boots have forward lean levers on the back of the boots.
These should be released when walking, hiking or skinning. Experiment with the setting to see how much forward lean you like when turning. I know a guy that leaves them up even while skiing down, he prefers the cuff to move. I don't recommend this but try the various settings if you have them. Also on the T-1 note the cuff cant control.