True there hasn't been any written reviews on the XP3, but I know there are some comparisons on them.
I own the Rena FilStar XP3 and the Eheim Pro II 2128. Both are rated for about the same size tank, with the exception that the Eheim has a built in heater. I use an ETH201 200 watt inline heater with the XP3.
1. The XP3 hoses were not as rigid as the Eheim hoses, so I replaces them (XP3) with the Eheims. Since the hoses remained behind and under the tank, the color of them didn't matter.
2. Except for the filter pads and flosses, I didn't use the media available for the XP3. I had some left over media from my 2128, so I used the excess Eheim media to fill the baskets in the XP3. Strangely, the amount I had was more than enough to fill all the baskets of the XP3, using the same media configuration as the 2128. I know the excess media is not enough to fill the baskets of the 2128, but was enough to fill the XP3.
3. The XP3 is noisier compared to the 2128. Both filters are being used on my 125 gallon tank. Both filters are next to each under, in an enclosed cabinet. If I turn off the XP3 and let the 2128 run, I cannot tell it is running, unless I bring my ear close to the filter. If I turn off the 2128 and let the XP3 running, I can definitely tell the filter is running, even from a distance.
4. The XP3 appears to have a faster GPH than the 2128, but I do notice that the XP3 does slow down faster when it clogs. I often compared it as Torque (Eheim Pro II 2128) vs. HP (FilStar XP3). Although the XP3 has faster flow rate, the 2128 appears to keep the same constant flow as the pads collects detritus.
5. The casing on the XP3, as you mentioned, does appear not to be as sturdy as the Eheim, which doesn't really appear to be a major difference.
125 gal (473 liter): Low Tech
(1.5wpg PC for 10 hours, no CO2/ferts, gravel substrate), Equipment
(72" Coralife PC, Eheim Pro II 2128 w/built in heater, FilStar XP3 w/Hydor ETH201 inline heater), Fish
(6*Discus, 2*Angel, 5*Clown loaches, 4*L-018 Gold Nugget pleco, 1*L-260 Queen Arabesque pleco, 7*Cories, Farlowella cat)