Hi there!
Just finished my LT3652 design (started at 2011.04., test started 2011.06, nice summer time, corrected major issue and get full power 2011.12.), and at first, i was scared to hell too. I used Alu-elco conds for Cin and Cout (low ESR, 3-3 paralelled), and SK54 Schottky diodes. For Vin solar protection too. When i tried to charge a battery, i got almost the same issues. Panel (4 layer with power plates) got very hot, not just the IC itself, but the Cin Cout array too. My Icharge never got above 500mA, no matter what i did. And, the charging stopped if i put some load on it, even if i got 500mA from solar, and loaded only with 300mA. Technically, always had an enormous leakage. After some months break, i just deciced to change something. I was very lucky, because my Alu-elco footprints made myself, so i was be able to solder Tantalum condensators, instead of Alu-elco. Magic happened. My Solar panel (23V Vo, 17V MMP, 0.7A Imax) did its max, at december sunlight!!. The circuit managed to float my solar panel at 17V, and charged my akku with its programmed max 1.0A! Approximately. Almost all the heat disappeared, now just the IC itself gets warm (lot colder than before), and all capacitors and diodes are cold.
So, i hope anybody reading this who needs some tips about this really marvelous IC in this low-power category. Use tantalums, they rulez
A.