I was just on my 15 inch laptop which has the 1300x900 screen and it is totally different then my 1920 HD screen. Just seems easier to visualize on the larger higher definition screen. If the 17 or 18 inch screen is what works for you and you do trade mobile a lot from hotel rooms, etc. then just go with that and just find a way to tote it around. I couldnt imagine trading on the 15 inch low def laptop or a 10 inch tablet. If I was going on a big trip, then I would find a way to take my 18 inch laptop.
I am firm believer that speed of data comes first before anything else, most of the software platforms can't even use the faster machines, so spending money on what is not used is just a waste. Only reason I even have two laptops is one is for email and I have used the 17" latop for so long, am just use to cramming eight charts, five of them are longer term in nature, so I only check them every hour or fifteen minutes. It is amazing what the eye gets trained to see after awhile. Actually, I believe that less is much better for the trader, less screens, PC's etc...
Im using my big 18 inch right now and its so much easier. The monitor on the laptop is outdated 3-4 years, but it looks a lot better then any tablet or 14 inch screen.
I have a 17inch HP and a smartphone. I used to run Amibroker powered by Esignal alongside Oanda. After a year or so, I came to trust Oanda's feeds, and realized that I while I had a lot of neat stuff on my charts, I was actually trading off the candles themselves, so got the Oanda app for Android to see if it would suffice, and I have to say it is wonderful.