NHT X1 Crossover

From what I understand this crossover was designed as a part of a complete system released by NHT years back. While I don't have nht products, I do have a subwoofer in need of external crossover. I just ordered the X1 last night from a fellow audiogoner, however I spoke to a rep from NHT via email and he said that this crossover was designed specifically for the Evolution subs and to be mated with the system it was designed for. Here is a copy of what was written to me....

Dear Sir,

You can use other amplifiers than NHT with X1, but with other than NHT subwoofers you might have some troubles. X1 was designed to match our Evolution-series and in-wall subwoofers, not be used as a generic crossover.

Dear Sir,

Crossover slopes, boundary EQ’s, pretty much everything in X1 was designed for Evolution-series subwoofers. Evolution subs don’t have passive crossovers inside them, so that is why we designed X1. If you use some other manufacturer’s subs, you may and most probably will face problems in sound, because X1 may lack some features that sub requires. That’s why I either recommend using NHT Evolution-series subs, or using a generic subwoofer crossover instead of X1.

These are the first and follow up responses I was given when asking about the x-1 in my system. Would you take this with a grain of salt since they might want me to by one of their subs, or do you believe there is merit in his claim. Thanks to all!
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My NHT X2 is coming in the UPS tomorrow. I'll report back how it works with my generic sub.
Thanks wavetrader, but the issue at hand is the x1. I understand the x2 is good for any sub but the x1 is not designed to work with any sub.
Hey anyone heard of the audio control ricter scale. I decided to issue a return with my seller so I won't be receiving the x1.