Hi young onset
yes i have done this, not through choice but I changed countries and XL is not available (don't let me get started!). I have found it has taken a long time to adjust, maybe 3 months, i had been 5 years on XL. Like you i was on 14mg XL and im also on madopar. I stayed on 12-14mg ropinerole short acting, i thought the amounts are approx. the same whether long or short acting.
So how do you fit in three hourly madopar on empty stomach and 3xs day ropinerole with food!! What i have ended up doing is taking 2mg ropinerole with every madopar dose. I can tolerate 2 mg without food but not higher dose. This also has helped lessen (though not avoid) the sleep attacks i get from short acting ropinerole. So i take madopar and ropinerole at 8am 11am 2pm 5pm 8pm and a 2mg dose of ropinerole only before bed with a spare during the night if i need it. I worked this out myself and it suits me now but my aim was to try and give smooth continuous treatment.
Do hope this detail is helpful.