If you have the money, IMHO, the IPS-1 over the LPA-1 is a no brainer. I think the difference in cost is about $400. Amortized over a min ownership of 10yrs,...see where I'm going with this?
Performance wise again looking at pictures on Emo's site you can clearly see the build upgrade of the IPS-1. Think of it this way, you could put AA batteries in series to get the same power rating (volts) as a car battery. Which setup would you want to start your car or which do you think can produce more current?.........Anyways, good luck with whatever decision that you make. Just make sure that it will be an upgrade over your existing equipment.