The only thing I'd say about the speakers is: beware. I bought some of the original Motive 1 and they developed so much bass as they ran in that they had to go. Nothing I could do would tame it - total nightmare. I've never got reflex ported speakers to work in my room, so it may be the room rather than the speaker. The transmission line PMC twenty.23 worked beautifully though. And of course, the new Motive 1sx might be less of a bass monster.
This is probably not helpful, but if you are thinking of changing electronics, it's probably best to do that first. A big amp and small speakers will very likely be better than the opposite. The Motive 2 has always been a more balanced speaker than the 1. The other advice I'd give you is to consider used or exdem speakers. They are far cheaper and you can sell them on with little or no loss if they don't work out. A new £2,000 speaker today will be worth £1,200 tomorrow.
Oh no did you not see my previous post about being decisive?!!! I have read your previous posts about the Sx1's but so far the bass seems very well controlled and only overblown if the mastering isn't up to scratch. I would say 80-90% so far is perfectly balanced. They have obviously been redesigned to counter this problem with better bracing, new cross over components and altered port tuning from what I have read. I had planned to do a home demo of pmc 25/23 but this maybe too much speaker for my current amplification. Having said that cost wise with flatcap it's about equal. My head hurts. :-)