Titan effectors are completely articulated 'snakes'.
daVinci Xi effectors are 'wristed' articulation.
I don't think for these reasons patent conflict exists. Could be something else though.
I think more likely Xi was put on hold because adoption would be sluggish in this climate, at best. ISRG can afford to delay. ISRG will 'improve' and reintroduce Xi when it believes it can create a definite marketing stategy to counter/contrast with SPORT. Right now, assuming SPORT'S approval, ISRG doesn't know what SPORT will look like, how it will sell, etc., etc..
From April 2, 2014:
Canaccord Genuity analyst Jason Mills reiterated a Hold rating and $423 price target on Intuitive Surgical (NASDAQ: ISRG) saying Xi in "no panacea."
Mills said, "... we are hard pressed to get constructive on ISRG until we have greater clarity on adoption trends for the new system, as well as visibility for a next-generation single-site system."
Mr. Mills added "While the new system should help the company re-engage potential customers who do not yet have da Vinci, and could also drive an upgrade cycle at some existing customers, we do not believe that the Xi system represents a panacea for below average procedure growth trends."
Market Data 
Markets 
AI
