So I got the kid the 60052 Cargo Train for his birthday, and looking to extend the possibilities of the layout. His train table is 4' by 6' (122 cm x 183 cm), so there will be room to add a second loop and some switches, etc... I see that ME Models now has R56, R72 and R88 ABS curves for sale on BL. Which do you think is best, or combinations - suggestions greatly appreciated.