Ronnie is obviously very talented and has a precision stroke, so I would expect him to have no trouble pocketing balls. However, while Ronnie and other top snooker players separate themselves from other snooker pros with their ability to make very difficult shots, pool neutralizes some of that advantage because there are so few really difficult shots on a pool table if your position play is good.
I think it would take a little longer for him to find the limits when cheating a pocket, banking, or shooting down a rail. There are a lot of standard shots in pool that are extraordinary shots on a snooker table, so your shot selection and position play needs to adapt to take advantage of the additional possibilities. The good news for him is that everything that goes on a snooker table still goes on a pool table; this is probably the most significant reason that it's easier to go from snooker to pool than the other way around. If you're a pool player going to snooker, there is an "unlearning" process involved in the transition whereby you actually reduce your arsenal of shots. For snooker players going to pool, it's all about expanding your repertoire.
I'd also say that there are challenges particular to specific games. For 10-ball, he'd have to develop a solid break. For 14.1, he'd have to get used to moving around in tight spaces. For 1-pocket, well, that's just a totally different game that requires experience to play at a high level.
