Hey, just wanna pick your brains - do you think it's worth it to get a replacement stainless steel GPS/Cellular Series 4 for $99 (replacement because of weak battery) or just go for a new aluminium Series 9 with GPS only and less scratch resistant glass for $399? I don't really care for any features S9 has over S4 other than a slightly bigger display and better battery life, but the S4 will probably become obsolete in a year or two and might not get newer updates and I also don't use cellular on mine, otherwise the $99 price tag is really tempting and sorta feels like a bargain for basically a new watch.