This is my experience with KATO track for what it is worth.
In 2004 when I started to get things together for my new N Gauge layout I bought some KATO track and turnouts to evaluate it.
There was a KATO leaflet at that time which stated you could not run long wheelbase trucks (bogies) through the No.4 turnout.
On the turnouts the electrical contact to the rails were made using a crimp system (I haven't checked to see if the current models are the same) and I had two of these fail. I did solder the contacts but felt that it was a weakness I could do without.
Doing British steam outline I did not want to pay the £19.95 (todays price at MG Sharp £23.99) and then have to file the check rails to give the clearances to get stock through the turnouts without jumping.
With the overheight ballast the rail size and the 33mm track centres, together with the
very limited turnout selection, I decided to give it a miss and use Peco Code 55 thoughout.
A Peco medium turnout costs £9.10 + £6 for the motor add a PL15 microswitch assembly for £6.50 (Kernow MRC prices) so for £21.60 I have a turnout with more control functionality than a KATO which is £2.39 more.
I could not build this layout with KATO track
My Trackplan it is 3m x 1.8m and is based on using Tracksetta curves which is why it appears to be settrack sections, the smallest radius is 381mm (15").
If you do not fancy cutting track, laying ballast, making holes for turnout motors and can live with straight turnouts then my advice is buy some pieces and see if it suits you. I would think most of the more recently designed items should run on it OK, Dapol 6 wheel Milk Tankers do, I've just tested some whilst putting this post together.
I saw KATO track used on I think it was Ron Upton's layout Temple Falls yesterday at the Spalding show at it looked really good.
The KATO K1 standard set that I bought originally is used for testing and running in, Bachrus running stands fit on it very well when setting up CV's, so it was a worthwhile exercise and not a waste of money.
Chris