Shure PA411 with PSM 900

I'm in the process of purchasing some new wireless, but I'm trying to figure out how to NOT spend a crap ton on an antenna combiner. I have two PSM 900's and I'm going to get two more, which means I will for sure need some sort of combiner, and Shure's P421A (the combiner for the 900's) is $1800. Seems like a lot just to combine some antennas. I'm pretty sure I need an active combiner because the antenna location will be about 50 feet away, but if passive combiners would work for this I'm open to that as well. I'm wondering if Shure's PA411 would work for the 900's. They are advertised as being for the PSM 300 series, but after reviewing the specs it looks like they should be able to work with the 900's as well. All I'd have to do is slap a 1/2 wave antenna on it and be good to go. Does anyone know if this is possible? Or does anyone have experience with the PA411 combining PSM 900 signals?

Shure PA411 with PSM 900