Built-in phono stages

Lots of high-end preamps include built-in phono stages. Any opinions on whether the pros (well reviewed, fewer boxes / cables) outweigh the cons (flexibility)?

I'm thinking, in particular, of the phono stages in the preamps from Ayre, Boulder and Halcro.
Best is CAT.
My Mac preamp has a built in MM section. It works for me, though I have not tried anything else for awhile. But I am looking to see what else would be better. Everything I have read is that the mac phono sections are pretty decent.
I have the Halcro DM10 which has the built-in phonostage for both MM and MC cartridges with 3 stages of gain for the MCs so LOMCs are no problem (I'm currently running ZYX Universe and Dynavector DV1s).
The beauty is no interconnects and additional boxes as you state (my friend has the full Aesthetix Io Signature which takes up serious shelf space).
The phono stage in the Halcro is as good as the linestage and the DM58 monoblocks themselves.
Lack of flexibility?.....nothing prevents you from adding an additional phono-stage to plug into a line input any time you wish?
The phonostage in the Ayre is very good. Same board as used in the P-5XE. The best I have heard in a preamp. The K-1XE is also the one of best SS preamps I have heard.
I also got a chance to hear the new Mcintosh C2300 preamp and was suprised at how good the MC stage was in it.
VAC Renaissance Signature Mk. II
One of the poorly understood issues with preamps is that they must control the interconnect cable. The technology to do that, to obviate the effects of the interconnect cable, was developed nearly 60 years ago, but it rarely gets used in the home (that technology BTW is known as the low-impedance balanced-line system).

Outboard phono sections face this issue, just as line sections do: in most high end audio systems, the interconnect cable behaves like a filter, filtering not only frequencies, but impact and staging information as well.

The only ways to avoid this are 1) equip the stand-alone phono section with proper cable-driving ability (none that I know of have this BTW) or 2) build the phono section inside the same box with the line stage, thus avoiding the connectivity issue altogether.

Solution 2) above means that for best operation, the preamp's power supply rails had better be quiet! so as to avoid interaction.
I'm really happy with my Modwright SWLP. It has the SWP phono preamp incorporated into an upgraded SWL linestage.
The darTZeel full-function preamp is remarkable. It is in a different league above that of the CAT.
I used a Janus from Aesthetix and it was magnificent. I had to sell it to raise cash just recently, and boy was I sorry to see it go. My separates (Blue Circle linestage and EAR 834p) that I still owned went back into the main system, and what a disappointment it was to hear it! (And those are GOOD products!)
I'm a believer in integrated phono stages now. The one drawback is that many integrated phono stages do not have the gain and loading adjustments that we all want to have. The Janus did have gain and loading adjustments, however.

I am extremely happy with my Joule LAP 150 MKII full function preamp. The phono section is the Joule OPS-1 which is the same phono preamp that was used in the previous Joule preamps. It has 60 db of gain and the impedance can be varied but I just use 47K for my Benz Ebony.
I've had several full function Cats and while their phono section is quite nice for MM's and higher output MC's, anything less than around .5mv and you can forget it. I ran an Ultimate II with Klyne 7PX3.5 phono for a few years and loved that combination.

I'm currently running an Atma-Sphere MP-1 Mk3 w/phono and have to agree with what Atmasphere said regarding cables and separates. My system took a gigantic leap forward when I made the change. I was a bit skeptical about having enough gain to properly drive my .03mv XV-1s but Ralph assured me I'd be happy with the set-up and that turned out to be an understatement.

The MP-1 also allows for easy cartridge loading without having to remove the top; no soldering or DIP switches to mess with either. A couple threaded loading terminals on the rear panel above the phono inputs make for fast and secure attachment of any type of resistor you may care to audition.

A final thought, the three preamps you mention under consideration are all solid state. Before you pull the trigger you may want to audition a couple good tube units for comparison.

Having owned my fair share of SS gear in years past then moving on to tubes, I'd never go back; amps or preamp. I'd be surprised if you don't find tubes to flesh out images better offering up a more 3-dimensional and believable soundstage. Just another opinion from the peanut gallery!

I posted this in another thread...

"The build in phonostage in my Paragon 12A preamp and my Audio Note AN-6c or Koetsu (each with different cartridges) step up transformer. I've heard a lot of phonostages (owned a ASR Basis Exclusive and Audio Research PH5, E.a.r.) and even sold my beloved Gryphon Orestes phonostage since they all could't match the Paragons ability to make you focus just on music while listening."
The Shindo preamps all have built-in phonostages (except the very bottom Aurieges-L) that are absolutely world class.