If the padded straps interfere with stock-to-shoulder placement, then affix a sternum strap to the front of the shoulder straps.
You can easliy make one with some flat nylon webbing, a dual quick-release buckle, and a few tri-glide buckles. Such will slip on, be affixed in position, and pull the shoulder straps together in front with a minimum of cost and no sewing.
The main reservation I have about chest rigs are that the real estate is somewhat limited. That said, the common mistake is to overload the vest with mags, which makes it difficult, if not impossible to assume a good prone position. Personal protection issues are important, and assuming a low profile may someday be essential to your continued good health.
Aside from that, if you do manage to go prone and get into firing position, just how accessible are your mags? You are probably lying on most of them.
I think most chest rigs are niche items, and not at all desirable for most real world conditions. My own chest rig is an older Blackhawk PALS unit, no longer offered. On it I have mounted two 3X1 cell AR mag shingles, although it will accept three 2X1 M-14 mag pouches.
There is room on the back of the waist belt for a 2X1 mag pouch of either type, and that should not be ignored, IMHO, considering that some of the mags will be semi-inaccessible when in prone position.
Currently available are both woodland and desert camo USGI MOLLE vests, and for cheap. It might be wise to buy one, on the cheap, and do a little experimenting before plunking down serious bux on an untried system of carying your gear.
YOU must determine your needs, and thus the gear required to meet your needs. Besst to experiment a bit before committing yourself and a goodly bit of your cash.
To sum up: Nothing should interfere with you going as flat to the earth as possible, nothing should interfere with accessing at least most of your mags, and nothing should interfere with a good shooting hold. If anything interferes with any of these requirements, then re-think your gear.
For that reason, I prefer a vest, upon which I can distribute the mags (as well as other items) so that I can assume a good prone position, shoot well from any position, and access most of my mags in any position. YMMV.