INTRO competitors ?

Neat Mystique. Beats the Credo, even.
Royd RR1 is a competitor, but I wouldn't want to run them off a Nait3.
The Rega Ela is also nice. Should be a great match with your system and you'd save some coin.

I've owned them all, and the Neats are the best in every way. The Epos M15 is another strong contender, but I haven't heard them with Naim.
I prefer any of these of the Intro.

try this page: http://members.shaw.ca/mikesae/oldstuff.htm

Neat are, last time I asked unavailable in NZ. I have listened to the little floorstanding Rega ( Alya I think ? ) and that was impressive. So I will take a listen to the bigger brother, along with the Intro.

Improve the source and for free you get....
better sound from your existing speakers/amp/cd collection.
Better speakers will only show up any weakness in your system...telling you need more from your source...while bad speakers will only mask your weaknesses sounding ok in the short term but ultimately will prove unsatisfactory once you do improve the source.
Nothing bets experience........

I've owned Intro's and felt they never really took off until they were on the end of 3.5 hicap/102/180/hicap/napsc....I would recommend at least a hicap for the 3.5 and a 92 conversion for your nait 3 and then a 180.
Building on the fundamentals first, improved source via external power supply..more power/control via 180...then the worlds your oyster.
I have heard some rather dissatisfied Intro owners, but looking at the gear used to run them I'm not suprised..the Intro is an entry level speaker in price only.