For a die-hard player, a good graded hammer action keyboard is a must but really heavy to lug around or too damn expensive. Case in point is my Kurzweill SP-88. A great fully adjustable Fatar TP-10 keybed but it weighs 52 lbs. 
The sounds are not the greatest in this day and age but my tweaks render the pianos really good. 
Even so I would lug a laptop (a pretty powerful one) to handle Pianoteq with the SP-88 as a controller. 
Too much stuff and too damn heavy, so what to do? I bought a Casio PX-150 for $399 from Kraft. 
The going price is $449. The newer PX-160 is $499. So what do I lose by getting the PX-150 as opposed to the PX-160? The on-board speakers of the PX-150 are said to be not as good as the PX-160. I don't care. I will use my 2 dead quiet Yorkville (Traynor) KB-50 amps (easier than lugging my 2 Mackie 450's - the Italian one's, not Chinese - which I could also do to add another 50 lbs). The electric pianos and strings are supposed to be newer in the PX-160. I don't care. It's the piano and keybed I need. Not worth $100 bucks more to me for the better onboard speakers and strings. 
Otherwise the sound of the PX-150 is the same, supposedly as the higher end Casios. I read a lot about it and decided at that price to jump. Glad I did. The pianos sound great, are tweakable and the keybed is excellent and the thing weighs only 20 lbs. 
Okay, the case is plastic, but solid plastic, while my Kurzweill is wood and metal. But the keybed on the Casio is great. The keys feel great. Even the EP's, FM pianos and strings sound good enough. The organs could be better, but then I never really heard a good B-3 sound from any of these keyboards. With a Boss Leslie pedal there's an improvement however a laptop running VB3 would be the way I go. Even so, I really just wanted something to play solo piano or in an acoustic type setting without bringing tons of stuff and feeling like I could relax and just play piano or Rhodes. The PX-150 does the job. Now if Pianoteq could run on Android......... 
Did I say Android? IK Multimedia has released the iPad's iGrand Piano and the iElectric Piano for Android. I tried the free versions. Put the phone into Airplane mode and forget Bluetooth and there's really no noticeable latency.
The phone speaker does not do them justice at all. I plugged into the studio monitors and the sounds are more than decent. They actually sound pretty good and can be tweaked somewhat. Earphones sound really good too. Very believable and comfortable. The Casio sounds much better with 128 note polyphony and the "AIR" technology but the iGrand and iElectric are suprisingly good. For the price they are amazing. Perhaps toys but truly surprisingy good enough for some situations. Maybe in an emergency although I could not think of any scenario in which would I use them but to practice stuff while on the go, perfect with the IK iRig PRO Keys 37 USB which just came out. A tiny keyboard controller with 37 full sized keys that works with my Android. I put that to the iGrand and iElectric and latency is low enough to play trills etc. 
The keyboard is still small but open two handed voicings are possible. It has octave keys but forget arpeggios or multi-octave scale passages. It has transpose and all that and mod and pitch wheels. It will store 4 program presets and take sustain or expression pedals and is powered by the phone. It's pretty no frills but it's only $99. I took it to work today and on my lunch hour got in some pretty good practice time through my phone! This will work on buses, backseats, parks, hotels. I think it needs Android Lollypop and it works perfectly with the IK pianos on my LG G3. The IRig keyboard comes with Sample Tank 3 SE and some IK plug-ins and content for it which are worth more than the keyboard (I downloaded them but may never actually get around to use as I've got those bases filled by Scope and Kontakt, etc. but my kids could have fun!). Duly impressed, I got the full versions of iGrand and iElectric for less than $10 for the both of them giving me more than 40 different acoustic and 464 electric pianos, some are layered with strings, some are phased or chorused and while I pass on a lot of them like thumb-tack piano or hard coded effects there are a few that are pretty remarkable considering these samples are on my phone!!!! 
So... two problems that have been bugging me, solved. Bringing a lightweight 88 key piano to a gig that sounds and feels like a real piano and having a really portable multi-octave keyboard with some full size keys to practice or compose on anywhere I want that sounds like a pretty realistic piano. The Android stuff ain't no Steinway or Rhodes by any stretch but it is satisfactory enough for practice and maybe an emergency. These IK Android pianos do sound surprisingly pretty good through monitors or earbuds and the Casio is very satisfying through the KB-50's across the whole keyboard. With the amps about 4 to 5 feet apart speaker center to speaker center it's very convincing.
I don't feel any guilt or remorse about these purchases. The Casio will pay for itself with a couple of gigs and the iRig Keys and Android stuff brings in a whole other dimension for the woodshed.
The whole shebang cost me just under $520 and will definitely get used daily while traveling very light which is what I have been wanting with pretty much no compromises. 