Well, it looks like my original post vanished
and I could not sign on last night .. maybe a glitch? Oh Uncle Dave, I'm not sure about the question you asked me. Haven't tried tried the mic yet..but I played the 740 into the inputs of the mz and was able to use the mz onboard effects with the external sound source. The 740 sounds great coming thru the mz onboard sound system by the way. I recently purchased the MZ 2000 and have owned the 740 for over a year. I also tried out the PSR9000 but I just couldn't fork out the extra bucks right now. The 9000 was awesome and heads and shoulders above the 740 in features and dfunctions, but you would expect that at 2 and a half times the price. What was somewhat similar were the voices and the arrangements as heard thru headphones and later an amp, so I went in a different direction and got the MZ.
and still have a couple of bucks in my pocket
to eat with this week ..lol. In reading this comparison remember, this is what I hear from the boards, and I don't play out much right now. I compose at home a lot and someday hope I can get enough time to polish these compositions, so my needs and wants may be different than yours.

Ease of use: Both boards are easy to navigate
although I am still in the learning mode on the MZ. The MZ has more features tio be sure though. The manual on the MZ is clear to me and even though the board is different from the 740 in many ways, the experience I have with the 740 and a 530 before does help.
winner : even

Features: the 740 has some nice features but the sequencer is very limited. Of course it also has the vocal harmonizer ( which I dont use all that much ), the mz does not. Apart from that the mz totally outshines the 740 in the features dept. It has many of the features of a good computer based sequencer program including step sequencing and the ability to tear down parts of any standard midi file ( you have to convert to format 0 ) , and create user styles out of them. The mz has aftertouch 740 does not. Both have ample registration memories. mz stores 10 user styles in memory - 740 only 3. mz stores 10 user songs internally, 740 stores none. Both have disk drive functions so that additional user styles, registration memories and user songs can be stored on disk. Both have pitch and mod wheels and second pedal which controls variety of functions. For me though the shining feature of the mz is the built in synth. You can perform actual synth mods on any of the voices and so far seems to work great. You can also store 20 user voices internally and as many as you want on disk. One small disappointment on mz. Can't change sustain pedal polarity internally ( 740 can ). Can't use my current pedals properly so I have to purchase a new one.( they work backwards )
Winner : mz big unless the vocalizer is an essential function for you

Auto accomp: 740 has 160 internally, mz has 120. mz seems to be a bit smoother sounding but the 740 has better patterns overall. Both have similar functions for modifying built in styles, but it would appear that mz has more ability to apply effects and changes. Both have 4 variations per styl;s, 2 intros and endings. In addition MZ has rit and fade functions. 740 has huge advantage in that many styles are available on the net. Mz has virtually none and can use no other manufacturers styles that are available on the net. XG works software is my savior here. It also can use any of the correctly converted and readily available internal PSR styles like an arranger board does, so I can hear the yamaha styles on the mz and they sound good there. Also with the midi file to style conversion function on the mz I can convert any type of style to a midi file , load it into the mz, and break it back down to create an mz user style.

Voices : Pianos: 740 has gerat acoustic and those old cp and dx electric sounds. mz acoustic not as good but electrics are very nice. winner: 740
organs: both have awesome organs and drawbar
functions . winner : even
Accordians: even except the mz has awful harmonica sound. 740s is much better
Guitars: both have very good acoustic guitar sounds Mz has much better electric and distorted guitar sounds. winner MZ
Bass: acoustic and standard electrics winner: 740 , synth and tech basses winner : mz
Strings: both have great ensemble sounds but I don't care for the solio violins in either
winner: even
brass and horns: both are pretty good; winner: even
sax: both have nice sax sounds , but 740 gets the edge because growl function on sax responds to touch sensitivity, mz does not
Flutes: 740 gets the edge with that sweet flute sound
Synth sounds: both have nice internal synth sounds but the mz is a clear winner here with its built in synth function.
Drums: mz has 15 kits , 740 has about 13 if I remember right. sdtandard kits: I give a slight edge to the 740 here. Electric/ fx kits: I give the mz the edge here.

Key feel : Big edge to the mz.. It isn't the greatest out there I suppose but I really dislike the plasticy feell of the 740

Onboard sound system and effects: Both
have a ton of useful effects and some I could live without. MZ to me has a better sounding onboard sound system
Conclusion: If I HAD to choose between the 2 boards, and could keep only 1 of them overall for MY needs and wants because of its functionality the MZ would be the hands down winner. But since I don't there is no way I am parting with either. There are a few sounds on the 740 that the mz just can't compare to. My advice though is to spend some time with ANY board you plan to purchase ( I always do ). I know this isn't always easy to do unless you are near a guy like George Kaye. So few stores especiaslly here in the East have a good variety of mid upper end to high end arrangers, and the ones that do have a few don't have an abundance of people who know anything about the boards
Al M