I've never used a SP2 or SP3. I'm coming from a SP1 w/i5 4GB 128GB. What will I notice the most moving to a SP4 w/i5 8GB 256GB? I use PhotoShop, Canon's Digital Photo Professional, Word, Excel, Modern IE (tend to have a lot of tabs open, 20-40) and am often multi-tasking w/ split screen. I would like to use it outside more but it is unusable in direct sunlight. I rarely attach the keyboard. Will the SP4 be much of an upgrade?