e300 vs mx240 for border router ?

Hey nanog-izens So for routers that are touching our transit and (hopefully soon) future peering, we're looking at both the force10 e300's and juniper mx240's. The e300's are cheap but I have heard some rumors/talk of falling over when it has to deal with large numbers of prefixes and routes? The mx240's are nice but the cost difference is enormous. Does anyone have experience with e300's running into issues with large routing tables? Are there any tricks/tips that work around any issues (if they exist?) Thanks in advance Leslie