Upgrading 2 Velodyne FSR 12's - advice?

I'm running a 9.2 system with Kef Speakers - Marantz separates AV7005 and two MM7055's.

My two subs are Velodyne FSR 12's. They system sounds amazing once I got it tweaked. Now I'm wondering...everything is newly upgraded but my Velodynes are about 12 years old. I get them serviced ever few years and they are still sounding sweet.

The old FSR's are servo controlled. I'm thinking of updating to two Velodyne Optimum 12's, much more power but I'm losing the servo feature.

I'm not wanting to spend the additional to update/upgrade all the way to the DD 12's to get the servo amp control.

Should I just keep the FSR's 'till they puke which is unlikely, they've been faithful performers for a long, long time now. Would two Optimum 12's be an improvement????

Thanks for any insight.

I'm thinking the way of leaving well enough alone. Thanks for your comments. The Velodyne FSR's still do a VERY respectable job and are well integrated musically. Maybe I'm missing some extra punch for HT but there is enough there for all the rumble my room needs.

Thanks again.

And, thanks I'll check out the JL Audio E 112's.