Previously I was at the office and didn't have the time to bore you with a bunch of stuff you didn't ask about. First of all their customer service is top notch. They'll give you straight answers to anything you ask, and they'll do it promptly. They should definitely be a source to answer questions.
You mentioned doing the crossover upgrade, but if you are only going to do one of the upgrades I would upgrade to the standard 1TDX over the 1TD with superior crossovers. It's a cheaper upgrade and it will make a bigger difference. CSS will tell you the same.
When I upgraded the xovers and the tweeter I did find the top end to have increased detail, sparkle, and to be a more halographi... oh wait this is ASR I can't offer subjective opinions. I will say the difference wasn't huge and honestly I couldn't say with confidence that I could tell them apart in an A/B test. I like to think I could, but until I do a double blind test who cares what I'd like to think. I will say 9 times out of 10 I am disappointed when I upgrade audio gear.. this time I wasn't. I believe they sound better, and the money was worth it to me, but it's nearly double the price to do both upgrades. The base speaker is a heck of a value, after that It's still a great value, but you start to hit diminishing returns, but that's "HiFI" for ya.
I decided to measure them both tonight and compare, this is ASR after all. I used the moving mic method while playing pink noise, stood about 3 1/2 feet away, took three measurements and averaged them together with 1/12 smoothing. There was no EQ, and I only measured one speaker of each. Admittedly they were not in the exact same location, they were about two feet apart. They were pulled out at least six feet from any walls and there was definitely room for human error. In fact I would count on it. Below is a comparison of 1k to 20k.. below that they should in theory be the same. Red line is the regular 2TD, purple is the 2TDX with fancy pants xovers. Take this for what it's worth.. which should probably be nothing as the controlled variables weren't very controlled.
For reference to what I'm hearing when I'm listening to them in my listening position (I think it's about 8 feet away).. the below is with the PEQ and subs on. I obviously still have some work to do below 500hz. And I don't run the subs that hot for music.. unless it's for funsies.