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.
Remember Net Present Value from Finance Class? Sell and keep moving forward.
Post removed 
I never horde equipment, sell and move on.  Though I can't fault anyone for having a backup. 
Post removed 
Keep it. My personal experience is I regret parting with the majority of the equipment I sell. Make up a second system. Or a third. 
What I sold,i dont regret at all, my upgrade were to gain a certain minimum audiophile level... and I dont had the money to create my own historical individual museum...

Many people who sell are in the same way with a goal that is to touch the top...Cleaning is the secret to satisfaction, if you already had very good stuff, dont sell, clean the electrical line of the room or better of the house and the audio grid...This is the greatest of all upgrades for the majority of us...But alas! this truth is mostly unknown...I discover it by accident...The same system I wanted to sell yesterday is today so good that I cannot sell it or cost me under 1000 bucks all in all, but to upgrade it really will cost me around 25 thousand bucks...Cleaning is the secret...But cleaning is not easy and not a one-buy-product solution, it is more complex than buying...Read about cleaning before selling good gear...
Good - Keep.  Not good enough to keep - Sell.  
Keep it.  You will want to change things up on occasion.   Also you are very familiar with the BAT and obviously like it.  A good reference for your new pre.  
Post removed 
Sell the BAT. Keeping a spare of something that's repairable makes no sense. If you're going to use it once in awhile keep it, but don't keep it in anticipation of the new pre breaking down. 
I would not be in a hurry to sell it until I have listened to the new pre for a good length of time. Have regretted selling a piece of gear in haste, more than buying one. Doubt the BAT will depreciate much over the next year. 
I took delivery of the DS yesterday. Initial impressions ... more height and width to soundstage, more air around instruments and voices, lots of micro- detail, and more [email protected] to my system. No doubt, the "[email protected]" part (in terms of slam and impact) comes from the large output caps running my low impedance power amp and sub. Only have about 6 hours on the preamp, but I like what I hear so far. DS says the unit really opens up after about 50 hours, so we shall see. It's very different from the BAT, but I will not be in a hurry to sell the BAT, if at all. Evaluation periods can take some time.
Post removed 
of what use is it in storage?
Post removed 
At some point, I may consider a second system and can fit the BAT into that one. Also, I want to spend a good deal of time with the DS to ensure that I'm not listening currently with rose colored ears.
@rlb61, thanks for the update, please keep us posted on the developments.
Agree with your well reasoned approach to keep the BAT for awhile. I have let go of many pieces replacing with improvements and didn't look back. A few items like original, one off Dan D'Agostino satellite/sub speakers from the 1970's I keep out off pure nostalgia. My 1980's Thiels best them, but the D'Agostino's aren't too far off the mark. 

I too look forward to updates. Enjoy the music!
Admittedly, I am a hoarder of audio gear, specifically power amps. I recently sold the majority of my collection, mainly because : I would likely not use it; it was no longer gaining monetary value; I was able to emotionally let it go; I was not willing to invest in upkeep / rebuild; I was made an offer I could not refuse; I needed to emotionally detach myself from the piece ( oh, I mentioned that already, lol ). In my 50 years of involvement with high end audio, I do have half a dozen regrets of selling a piece, which is a small % of the amount of gear that has passed through my doors. I have 3 complete systems set up throughout the house ( had 4 until recently ); still have enough gear to set up another system, or 2. I only listen to my main system. Moral of this not become a hoarder. It is a sickness.