If you don't need the performance of the quad core CPU and stronger dGPU the HP make for a compelling package, especially being a 360 2 in 1 with full pen support. I find my Surface Book's custom 940M offers a nice uplift in graphic performance over iGPU.
What I think is; if your satisfied with your Surface Book's performance the 15" 360 will be more so, thx to 7th Gen CPU (marginally) and the dGPU. HP has made huge strides in it's design and quality, that said I've never personally had issue and still have an old DV2 that runs, which has seen off several Mac's
Q-6
Although generally Quad core CPU should be better there's always exceptions due to possibly poor programing that may well only use 25% of the available CPU although I understand hyper threading can assist in these cases, sometimes.
I doubt if we could find a list of such programmes but I'm struggling to find one for programmes/software that use quad core. Theirs lots of generalisations (eg Video editing) but I was hoping someone kept an up to date list for MacOS and Win10 so we can be sure we are not over spec'ing or even wrongly disappointed by choosing dual core for no good reason