The different in handling a 34' vs. a 39' as your first big boat wouldn't be that big of a deal. Just get a simple paint job so it can be touched up easy.
And make sure you get the bow thruster.

Can't make a bad choice, but if cost is not an issue go for the 39! Invariably, at a "trendy" hot spot you will be "one upped" by a 39 if you buy the 34. Most likely happen on your first day out! LOL

+1, I thought I was a better Captain than I am and saved the $$ on a bow thruster, MISTAKE

I think the 34 rode great. I sea trialed some others and it truly felt like a GT3 compared to everything else lol quality, build, performance, ride etc everything was first class about the nor-tech. I see the 400R popular on 39, what's the downside of trip 400s on 34, seems like the hull is pretty capable to get into the high 80mph range if you wanted to. Is it basically resale/warranty?

Also, it seems like it's time for Merc to come out with an even more tuned V6 R or more likely V8 Verado...any insider info on that? Nascat, if I recall, your first build was during the 350/400R release, did you time the build accordingly or just get lucky?

IMO one will not benefit from triple 400's on a NT 340 w/ the exception of acceleration which is already pretty strong w/ triple 350's. I ran both my 340's WOT w/1/2 fuel. 2 on board and they ran 80-81mph. This is not a comfortable place to be trimmed way out w/ the hardtop catching allot of air acting like a kite. It's a white knuckle ride at best & the chine walking is unnerving and unsafe. Both my boats were optioned w/ 380 K-Planes (std is 280) & while I can steady the ride, dropping the tabs scrubs off the speed. A Triple 350 powered 340 can run 75-77 comfortably all day w/ fuel and passengers. I don't see the benefit nor return on investment going w/ triple 400's on a 34' Nor-Tech. I'm also not a "All Show No Go" guy so cowls that have $)) plastered all over them does nothing for me. The 350 & 400 are the same engine just a different ECU tune. I recommend the 350's and get them turned up if you want the power of 400's. You'll void your warranty but have $15k in the bank.

Yes I was lucky, my boat was painted and out on the floor being rigged when I attended the 2015 MBS to learn of the new Merc Verado offerings. It was spec'd to have triple 300's but EVERYONE insisted I upgrade to the 350's to maintain resale value. It was great advice and paid dividends as I believe my 2015 NT 340 was the first on the resale market w/ triple 350's thus no others to compete with.

How fast is a twin 350 34 NT? For the sake of simplicity (twins vs. trips) and weight the twin should be a decent alternative.

I can't answer that w/ any sort of confidence but I believe it's in the 68-70mph range.
I notice that Randy Kent often orders NT34's in a twin configuration but thats bc his market is LOTO.

My original spec when ordering my 1st Nor-Tech was twins. What one has to get their head around going this route is resale. The market interested in a twin 34' Ctr Console is going to be limited. Other than twin engined 7 Marine Nor-Tech 340's or 390's I rarely see twins anywhere coastal. Most Nor-Techs will be found in coastal areas. Tenders could be another market for a twin NT 340 but typically anyone buying a tender is buying new so again limiting resale opportunities.

One of the reasons I let my perfectly good NT 340 w/ Triple 350's go recently was the rumor / fear of Merc Introducing a Verado 500. If Merc offers something that large I think the used triple engine NT 340 resale market will take a hit w/ many stretching to afford a new high H.P. twin 340.

Just a hunch.

I definitely wouldn't tune the 350 and void warranty!!
And my question of timing is exactly because of the rumor mill of potential 500s being released. I think a trip 500 39 would be ideal! In fact would even lead me to hesitate starting my build too soon because of it.

Are the 39's with trip 400s experiencing the same lift from the hardtop when in 80mph range as well? Assuming a quad 400 boat definitely feels the effects of lift if they are in the 90mph range. Also, I would likely go with standard hardtop version but, is there anyone with the extended top who's complained of tincreased kite phenom?