Question about the benefits of a stainless coil former

[shredder2]

It's recone time for my sub, I lost a coil and since I have a daily sub with my RS Plat 18 I'm trying to find some gains with my current box/amp setup.
It's for a FI Blv3-18 and I was originally thinking D.7 coils to wire lower along with an extra spider to control the mass with the added power, wired like I was at .5 I could make the coil tap at full power. That was with a standard FI recone dual 1 coils /w/ 3 spiders.
FI said the D.7 aren't available currently and offered a True dual 1 /w/ stainless former as an alternative for a burp only setup.
What I'm wondering is since I have a daily sub and will use the FI for burps only what will be the major changes with the stainless former?
Different weight? will the added metal in the motor add force or something like that.. or will the added mass be a wash with the motor force increase or will I need an extra spider?
I'm thinking the stainless former coil might be a tighter gap because it's for only burp applications and also the coil won't handle heat as well...  ... I've been warned... "being stainless on the former and aluminum on the winds, it has a dissimilar expansion ratio and will not take long term heat for music. Gains for burps, will unwind on high power music."

My coil WAS tapping at full burp...

 

But it ultimately failed here...

 

I was consistently clamping around 3K or so at .5, How will the "stainless former", "true D1 coils" affect my clamp and should I get that extra spider this time?.. I ordered it with an extra last time but upon inspection it has the standard 3 spider pack.

Depending on tuning (41-45hz) I've been clamping 2800-3500 watts at 47hz for a 152.4db consistently before. What happens now?

Any thoughts and advice from you more experienced guys would be welcomed before I order the new recone.
I'm assuming a lot but know enough to ask before diving right in.
Please help me understand this better.

Thanks in advance