The J. Mason stroller is not worth the money. Once your babe is over a year you will have trouble with them fitting into the stroller. I've also read how people have had the frame bend on the stroller, once their children are older. ( go to the triplet connection website & read all about it). I used the J. Mason for 2 months after my triplets were born & ended up taking it back to BRU & getting my money back. The front seat has only a waist strap & whoever was in the front kept sliding down. My then 3 yr old would fit only (barely) into the front seat of the stroller. I bought a Peg Perego triplet stroller secondhand from a fellow triplet mom for $200. It has been well worth the money. I have the older model. The only disadvantage is that I have to partially take it apart to fit into my van, but it takes me less than 2 minutes to put it together. On occasion my older dd has sat in it (plenty of room for her). The Runabout is another triplet/quad stroller. It steers a lot easier than the peg ( it is the stroller i wish that I had gotten, but the price was right for the other). You can find these strollers either through local Mother's of Multiples clubs (used) or online at the Triplet Connection site- they have used stroller listings by state.
BTW my triplets are now 2 yrs & we rarely use the stroller anymore, they just don't want to sit in it. When we go for walks they love to sit in their Choo-choo wagon. Each child has their own compartment to sit in-you can attach up to 7 cars. The first car has storage space under the seat & each car is a different color. I pull my 4 around the neighborhood everyday. It's made by step2 & you can even get seatbelts for it. I think I paid less than $100 for it.
HTH (probably way more info than you needed!)
Beth Mom to Megan-almost 5, Rachel,Zach, & Ashley- 2 yrs