Yes, but you also have to think about the difference vs regular equipment, which already have +more to an attribute.
[Note: 1 seasons' XP, post lvl 30 = 3*1000 (boosting) + 40 * 25 (daily) + 16 * 100 (game) = 5600 = ~5.5 levels/season]
Say you're a lvl 30 booster, started in season 1, and find a piece with +3 to something good (speed/agility/vision). That +3 counts as the first level of equipment, so fully upgraded it will be +2 compared to normal equipment. But at 32, your normal equipment will be at +5, so you're really getting -2 net to your attribs, in exchange for maybe a good 2nd bonus (+1 Shutdown, or +5% Intercept/Fumbling/Deflecting, if you're incredibly lucky enough to find a piece like that).
2 seasons later (S7), you could upgrade your custom a max of 3 times, to +6, but you'll now be lvl 41 and have +6 standard equipment available anyways - and you've given up 8 SP.
2 more seasons (S9), you're lvl 52, and thus have +7 normal equipment available. Your advance item gets another +3, pushing it to +9, so now your 1 advanced piece is fully upgraded and a massive +2 stat & whatever other bonus it has better than normal equipment. It's cost 16 SP to get here, so you're breaking even if that stat is going above the 8:1 cap, which according to some slow building teammates of mine is 83.26. That seems pretty reasonable, in fact I wouldn't be surprised if people were over 90 by that point.
Season 10, you'll start at 57.5 and have access to lvl 56 equipment, for +8 standard. That means another 10 tokens to boost the advanced, so with the other 6 you can get 1 SP. The pure SP-buyer will get 4 more SP, bringing him to a total of 20 by the end of season 10 - +19 SP on you that could've been spent anywhere else. Your net +2 is now only worth it past the 9.5:1 cap (9:1 = 85.59, 10:1 = 87.61).
By season 11, your player will be in decline, whatever that means. You'll be starting at lvl 63, which means lvl 64 equipment (+9) will become available sometime during the season, so that's another 10 tokens down the drain to keep your massive +2 alive. The SP-buyer gets +3 net SP, for a total of +22 SP compared to you, so the +2 you're getting from the advanced needs to be past the 11:1 cap.
Season 12 is great, except for the further player decline. +5.5 more levels means you're lvl 68.5, so no new equipment yet! You can buy all 4 SPs, along with your SP-buying buddy, and stay at the 11:1 relative need.
So yes, your 1 piece of Advanced equipment will be better than just buying SPs - and just in time for your player to start entering the 'decline' phase of his career, as well! Plus you've got that nifty little +1 to an SA, or +3-5% to something.. that is assuming you shit four leaf clovers and are lucky enough to find a piece of advanced equipment that good. Otherwise you'll be spending that extra time training on normal and shopping for that 1 truly excellent piece of equipment, all the while falling further behind the SP-buying types. I hope that +1 SA you got is worth a lot of SP to make up for it!
In the case of a newbie starting out, it's about the same. You'll probably want to slow build for at least the first season in the D-Leagues, which means you'll be using normal training (much better for slow building since you can focus on 1 attribute). Then, when you start shopping, you won't be able to find any items as good; +2 will probably be the maximum amount to a stat you can find at that level, and the SAs/other boosts won't be as good either. But let's assume you saved up a ton of shopping tokens while slow building, and find something decent right away. If you settle for +1 net gain vs normal equipment, then that +1 has to be worth the entire amount of SPs you'll miss out on over the SP-buying option, and it'll still take several seasons for that 1 piece to catch up to regular stuff. And once it is upgraded, you'll get around +1 equipment level every 2 seasons, so every 2 seasons it'll fall 3 more SPs behind, just like above.
tl;dr: Advanced equipment in it's current state is barely worth the hassle at higher levels (takes too long to compete with normal stuff), and definitely not worth it at lower levels (nothing good's available). Multiple pieces definitely aren't worth it since they'll never be competitive.
