Mirage M1 or M3 vs M1Si or M3Si Series

I'm the recent proud owner of a set of well acred for original M1's but curious to know from, MxSi owners what the differences are sonically between these 2 fine sets of Audio design and manufacturing prowess.
Humm, not sure on these replies, let me reiterate, I am not sure. I was 'told', way back when, it was just a tweeter change. Furthermore, I owned a pair of M3 speakers, not si versions, and they were biwire speakers.
ok clarification here the original M1 was single wire only believe the biwire capability was an available option. then later all M1's started being produced with biwire capability standard this probably was the same with the M3 also. All Si models had the tweeter and crossover upgrades and biwire capability.
THIS IS NO BS! Way back when Chicago hosted the CES show I had a conversation with Mr. Paisley who was one of those responsible for the design of the original M1. We talked candidly about the M1 (which I owned at the time) and the soon to be released M1Si. He was very straight forward answering my questions. He explained that when they came up with the idea of the M1 it was meant to be a flagship type product which they planned to sell in very limited numbers ("a few hundred per year"). To their surprise, demand for M1's was huge and the current production could not keep up. The tweeter for example, was a custom unit, hand tweeked with tight tolerances. The crossover was also hand tweeked to each tweeter to get the best sound. When demand grew, things would have to change so the production could keep pace. The real reason for the tweeter upgrades was to speed production. The new tweeter had tolerances that allowed it to be used with no hand tweeking involved-and the "new" crossover changes were implemented to work with the new tweeter parameters. I never heard the M1Si in a side by side comparison with my M1's so I cannot give you a comment on any specific sonic differences. I can say however that I never felt the need to upgrade to the M1Si even after hearing them several times. I ultimately moved on to 2-way stand mounted speakers and do not miss the Mirage bi-polar sound. My M1's, by the way, were low serial numbered and were bi-wireable.
I have
2 pair of M1si's
1 pair of M1's
and 2 pair of M3si's
I'd like to sell the M1's & 1 pair of M1si's
the M3si's are in my home theater system & the other pair of M1si's are in my audio setup. I live in california (bay area)
so local pick up would be preferred since they weigh alot.
if you want pro shipping that could be arranged.
email - raptor1015@aol.com
So, in light of this discussion does anyone know if it is advisable to replace blown M1 tweeters with M1-si tweeters since I can't source M1 tweeters? Sounds to me like the si tweeters needed LESS hand tweaking (i.e. they had tighter manufacturing specs). I know the crossover points changed between the two models but that may be moot, if the tweeters were essentially identical in output and frq response in the required range.

Any advice about dealing with 2 defunct M1 tweets appreciated.