I use a HT112 with a separate power amp, an old Electrovoice 7300. (It's essentially the same as an IP but you have to lug around the power amp separately.) I think the poweramp that Jim put into his IP line is, like the EV 7300, open to a very wide frequency range and uncolored. So when looking for the right preamp make sure there is HPF to roll off undesired low end from your piezo pickup (ie, below 35Hz).
I've used Fdecks preamp with good luck, but switched to the Sansamp para DI for more tone shaping options. I was looking into the Fishman Pro Plat eq for bass as well, but haven't tried one yet.
I can't say enough good things about those Bergantino cabs. I think they are exceptional for both BG and DB.
I did try an IP112 briefly when a colleague brought one over for me to check out. It was relatively light weight, especially when you factor in you can keep a preamp in your DB gig bag. To my ears it sounded the same as the HT112 w/separate poweramp.