IMHO,
There is very little difference, I went from short haul to long in 3 days ground school, 2 sims and some line training when I was flying as an already experienced pilot...
It's not an issue! Particulary if you're flying a variant (B757/B767 - A320/A330)
Lots more things to consider but as an experienced heavy jet pilot you probably had worked out anyway before you we're told it on your groundschool/line training...
It's all about more money and more time off..!!!!