To Sell or Keep?

I'm awaiting delivery of a Don Sachs Model 2 preamp, which should arrive tomorrow; it will be replacing my BAT VK-3i, which I have had for about 15 years. Here's my dilemma ... if I really dig the DS, should I sell the BAT or keep it? On the one hand, BAT equipment has become pretty expensive (new and used), so I likely won't be able to get back into it if I choose to do so later on. On the other hand, if the DS preamp is really as awesome as claimed, then the BAT likely will be placed in storage. What would you do if you were in my position? Thanks for your help.
It's not a bad idea to keep a "back up" in case the new component needs repair someday or you send it out for an upgrade.I'm betting once you get your new DS you'll never think about going back:)
If you can afford to keep the BAT as a backup or perhaps a second system do so. Down the road should you decide to you can always sell it, but once it's gone it becomes harder to replace for your origional purchase price.
Post removed 
I never horde equipment, sell and move on.  Though I can't fault anyone for having a backup.