You don't give an indication of where you live and it can be important in your decision. Also remember that maps do not offer equal coverage over all North America or anywhere else either. IQ routing is better in large urban areas than smaller cities where the likelyhood of many TT users reporting highway data is rather low. As for static ALG images, there are not many areas covered.
OTOH, if you are likely to travel overseas and in need of additional maps, better get a model featuring the SD card slot. Higher end models feature larger much larger POI included database and could prove useful if you wander around without having planned your trip carefully. The larger maps of the 730 could help reassure you with the additional cosmetic details shown or could be of no importance depending on the type of person you are. For some, just the basic lines are sufficient and for others, they feel reassured the map fits better with the reality. Others just look for the next turn, its distance and time remaining.
If my XL-S was stolen tomorrow, I'd be looking hard at the clearance deals on the GO 720 from approved TT resellers. This would mean I could get the latest map and NavCore and provide the same functionalities as the 730 at a reasonable cost.