The only problem I've had with them is that its a ball ache to remove the rear wheel,usually have to undo the bolt for it to move around a bit to get the wheel out.
They will negatively impact the shifting, especially on the smaller cogs, because the guide pulley will be further from the cassette. Also remember that they don't affect capacity at all, so if you're running more than 1 chainring, you might end up with a very slack chain in the small ring/small cogs.
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It wasn't overly successful to be honest and quickly bought a long cage mech.
I may add it may have been my incompetence!
https://winstanleysbikes.co.uk/shimano-tiagra-rd-4700-10-speed-rear-derailleur?gclid=CjwKCAjwqvyFBhB7EiwAER786SYSnrrtYDCYc0IoWCxprwQR98J5si3yy1_Vn9XSX8OnCqWrZrgJghoCs2kQAvD_BwE#shimano-tiagra-rd-4700-10-speed-rear-derailleur-gs
It's just a hill. Get over it.